Small improvements in my-xkb layout (#652)

1. Add comments with explicit characters
   for easier understanding of the rules code.
2. Remove the whole patterns_x section, which is
   just outputting the same characters that would
   be shown if the input method is disabled.
3. Remove some rules that output the same characters.
4. Add some tests, and add test names.

I verified these with the xkb keyboard on Ubuntu.

Co-authored-by: Santhosh Thottingal <[email protected]>

Merge pull request #507 from santhoshtr/version-update-0.2.0

Version update 0.2.0

Merge pull request #314 from siebrand/11

Various fixes suggested by static code analysis