All other Samples write to temporary directory. DefinedNames samples
write to main directory, which (a) means they aren't stored with others,
and (b) they aren't ignored by git so look like changed files.
The tests are also simplified by requiring Header rather than Bootstrap,
making use of Helper.

Resolve XSS Vulnerability in the HTML Writer

There are no changes to code. Additional tests are added,
so that the following 6 items now have 100% test coverage:
- Comment
- DefinedName
- DocumentGenerator
- IOFactory
- NamedFormula
- NamedRange

Two changes to fix minor problems reported by Scrutinizer.

…1743)

This is a fix for issue #1735.
It adds tests for this situation, and similar situations involving
adding new sheets and accessing existing ones.
Coverage for Spreadsheet.php increases from 69% to 75% as a result.

* Fix for 3 Issues Involving ReadXlsx and NamedRange

Issues #1686 and #1723, which provide sample spreadsheets, are probably
solved by this ticket. Issue #1730 is also probably solved, but I have
no way to verify.

There are two problems with how PhpSpreadsheet is handling things now.
Although the first problem is much less severe, and isn't really a factor
in the issues named above, it is helpful to get it out of the way first.
If you define a named range in Excel, and then delete the sheet where
the range exists, Excel saves the range as #REF!. If there is a cell which
references the range, it will similarly have the value #REF! when you open
the Excel file.
Currently, PhpSpreadsheet discards the #REF! definition, so a cell which
references the range will appear as #NAME? rather than #REF!.
This PR changes the behavior so that PhpSpreadsheet retains the #REF!
definition, and cells which reference it will appear as #REF!.

The second problem is the more severe, and is, I believe, responsible
for the 3 issues identified above.
If you define a named range and the sheet on which the range is defined
does not exist at the time, Excel will save the range as something like:

'[1]Unknown Sheet'!$A$1

If a cell references such a range, Excel will again display #REF!.
PhpSpreadsheet currently throws an Exception when it encounters
such a definition while reading the file. This PR changes
the behavior so that PhpSpreadsheet saves the definition as #REF!,
and cells which reference it will behave similarly.

For the record, I will note that Excel does not magically recalculate when a
missing sheet is subsequently added, despite the fact that the reference
might now become resolvable. PhpSpreadsheet behaves likewise.

* Remove Dead Code in Test

Identified it after push but before merge.

* Apply Column and Row Styles to Existing Cells

This is a fix for issue #1712.
When a style is applied to an entire row or column, it is currently
only effective for cells which don't already contain a value.
The code needs to iterate through existing cells in the row/column
in order to apply the style to them.
This could be considered a breaking change, however, I believe that
the change makes things operate as users would expect, and that the
existing implementation is incomplete.

The change also removes protected element conditionalStyles from
the Style class. That element is an unused remnant, and can no longer be
set or retrieved - methods getConditionalStyles and setConditionalStyles
actually act on an element in the Worksheet class.

Finally, additional tests are added so that Style, and in fact the
entire Style directory, now has 100% test coverage.

* Scrutinizer Changes

Scrutinizer flagged 6 statements. 5 can be easily corrected.
One is absolutely wrong (it thinks iterating through cells in column
can return null). Let's see if we can satisfy it.

* Remove Exception For CellIterator on Empty Row/Column

For my first attempt at this change, which corrects a bug by updating styles
for non-empty cells when a style is set on a row or column, I wished to make things
more efficient by using setIterateOnlyExistingCells, something which the
existing documentation recommends. This caused an exception to be generated
when the row or column is empty. So I removed that part of the change while I
researched what was going on.

I have completed that research. The existing code does throw an exception
when the row/column is empty and iterateOnlyExistingCells is true. However,
that does not seem like a reasonable action. This situation is analagous to
iterating over an empty array, and that action is legal and does not throw.
The same should apply here. There were no tests for this situation,
and now there are.

I have added additional tests, and coverage for all of RowCellIterator,
ColumnCellIterator, and CellIterator are all now 100%. Some of my new tests
were added in new members, because the existing tests all relied on mocking,
which was not the best choice for the new tests. One of the existing tests
for RowCellIteratorTest (testSeekOutOfRange) was wrong; it issued the expected
exception, but for the wrong reason. I have added an additional test to
ensure that it fails "correctly".

The existing documentation says that the default value for
IterateOnlyExistingCells is true. In fact, the default value is false.
I have corrected the documentation.

* More Scrutinizer

I believe its analysis is incorrect, but this should silence it.

* DocBlock Correction

ColumnCellIterator DocBlock for current indicated it could return null
or Cell, but it can really return only Cell. This had caused Scrutinizer
to complain earlier.

* PHP8 Environment Appears to be Fixed

Cosmetic change to Doc member. I suspect there is a way to rerun all
the tests without another push, but I have been unable to figure out how.

This had been intended to get 100% coverage for TextData functions, and it does that.
However, some minor bugs requiring source changes arose during testing.
- the Excel CHAR function restricts its argument to 1-255. PhpSpreadsheet CHARACTER
  had been allowing 0+. Also, there is no need to test if iconv exists,
  since it is part of Composer requirements.
- The DOLLAR function had been returning NUM for invalid arguments. Excel returns VALUE.
  Also, negative amounts were not being handled correctly.
- The FIXEDFORMAT function had been returning NUM for invalid arguments. Excel FIXED returns VALUE.

* Replace voku/anti-xss with ezyang/htmlpurifier. Despite anti-xss being a smaller footprint dependency, an a better license fit with our MIT license, there are issues with it's automatic it sanitisation of global variables causing side effects
* Additional unit tests for xss in html writer cell comments

…e not 0 (#1627)

* Fix bug where values of 0 were "rounded" up/down as if they were not 0

Issue has been marked stale, but ...
Sylk read sets worksheet title to filename (minus .slk).
If that is >31 characters, PhpSpreadsheet throws Exception.
This change truncates sheet title, as Excel does, to 31 characters.

The condition is FALSE if the cell does not exist in the flipped table,
but anyway, it is sent in to a method requiring 'string' type, causing
it to fail.

Resolve problem with incorrectly defined hyperlinks

* Add 'ps' suffix to printer settings resources IDs

Scrutinizer reported a minor error in a test involving a module
which I was not changing.
Styles/Conditional function setConditions can take a scalar or an
array as a parameter, but DocBlock says it only expects array.
I did not wish to add the extra module to my PR, but made a note to
self to fix that after PR was installed.
That has now happened, and it makes for a good case for me
to see all the PHP8/Composer2/etc. changes that have happened recently.

* Merge pull request #4 from PHPOffice/master

* Restore Omitted Read XML Test

* Fix for Xls when BIFF8 SST (FCh) has bad Shared string length

* CSV - Guess Encoding, Handle Null-string Escape

This is in response to issue #1647 (detect CSV character encoding).
First, my tests with mb_detect_encoding indicate that it doesn't work
well enough; regardless, users can always do that on their own
if they deem it useful.
Rolling my own is also troublesome, but I can at least:
a. Check for BOM (UTF-8, UTF-16BE, UTF-16LE, UTF-32BE, UTF-32LE).
b. Do some heuristic tests for each of the above encodings.
c. Fallback to a user-specified encoding (default CP1252)
  if a and b don't yield result.
I think this is probably useful enough to include, and relatively
easy to expand if other potential encodings should be considered.

Starting with PHP7.4, fgetcsv allows specification of null string as
escape character in fgetcsv. This is a much better choice than the PHP
(and PhpSpreadsheet) default of backslash in that it handles the file
in the same manner as Excel does. There is one statement in Reader/CSV
which would be adversely affected if the caller so specified (building
a regular expression under the assumption that escape character is
a single character). Fix that statement appropriately and add tests.

Now supports all current UoM in all categories, with both 1- and 2-character multiplier prefixes, and binary multiplier prefixes, including the new Temperature scales

Sync Fork With Base

This fixes issue #1789.
As originally reported, stricter typing was causing PHP8 to throw
an exception when a non-numeric value was passed to the Round function.
Previous releases of PHP did not see this problem, however, on further
analysis, they were also incorrect in returning 0 as the result in the
erroneous situation, when they should have been returning a VALUE error.
Yet more analysis showed that other functions would also have problems,
and, in addition, might not handle invalid input (e.g. a negative length
passed to REPT) or output (e.g. NAN in the case of ACOS(2)) correctly.

The following MathTrig functions are affected:
ABS, ACOS, ACOSH, ASIN, ASINH, ATAN, ATANH,
COS, COSH, DEGREES (rad2deg), EXP, LN (log), LOG10,
RADIANS (deg2rad), REPT (str_repeat), SIN, SINH, SQRT, TAN, TANH.
One TextData function (REPT) is also affected.

This change lets PhpSpreadsheet validate the input for each of these
functions before passing control to the builtin, and handle the output
afterwards.

There were no explicit tests for any of these functions, a fact made
easy to ignore by the fact that PhpSpreadsheet delegated the heavy
lifting to PHP itself for these cases. A full suite of tests is
now added for each of the affected functions.

Only in 3 modules which are part of this PR.

Return DIV0 error for TAN when COS is very small.

Results which should be infinity, i.e. DIV/0 error.