Support disable-bold,real-underline and native reverse-color.

[hymkor]

I tried to use ESC[22m to disable bold when ENABLE_VIRTUAL_TERMINAL_PROCESSING is not set, but it does not work as expected.

I made the test-code to compare before/after setting ENABLE_VIRTUAL_TERMINAL_PROCESSING.

The result is the picture below. <%d> means text decorated ESC[%dm

(On the default browser view, it is not clear whether the bold is set or not, so please click image-area TWICE to see clear-screenshot)

I created the patch to reduce the differences.

• ESC[22m disables bold.
• ESC[27m never makes colors reversed. It disables reverse set by ESC[7m only.
• ESC[4m enables real-underline which is not bold.

The image below is the screenshot when sample.go runs on Windows8 VM. (Please ignore After EnableColorsStdout)

Would you like to merge it if problem does not exist ?

[codecov-io]

Codecov Report

Merging #50 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master      #50   +/-   ##
=======================================
  Coverage   90.00%   90.00%           
=======================================
  Files           2        2           
  Lines          40       40           
=======================================
  Hits           36       36           
  Misses          4        4           

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[mattn]

Thank you