GimpCheatSheet: Add GIMP cheat sheet module.
GimpCheatSheet: Add tests.
GimpCheatSheet: Add more triggers.
GimpCheatSheet: Neaten CSS.
GimpCheatSheet: Add more spacing between sections.
GimpCheatSheet: Remove unused CSS rule.
GimpCheatSheet: Remove margin between columns.
Merge pull request #549 from elebow/gimp-cheat-sheet

Gimp cheat sheet