Add new Lint/EmptyBlock cop

[fatkodima]

This cop checks for blocks without a body.

# bad
items.each { |item| }

# good
items.each { |item| puts item }

Blocks without a body most of the time indicate useless code (left after refactoring, for example) or that some explanation about its emptiness should be given (using a comment).

[bbatsov]

I'm guessing an empty one-line block with a comment after it would fine as well. E.g.

x = ->{} # no-op

[fatkodima]

I'm guessing an empty one-line block with a comment after it would fine as well. E.g.
x = ->{} # no-op

This will conflict with Style/InlineComment

How about preceding comment then?

# no-op
x = ->{}

[marcandre]

This will conflict with Style/InlineComment

That cop is (thankfully) disabled by default. In any case, inline comment should be supported.

[fatkodima]

Added support for inline comments.

[bbatsov]

Great work!