Theme name must be the same as file name (as it is then shown in
Drop-down menu)
Update icon; use it in preferences
combo to apply theme globally
update docs, comments
fix "Cannot refer to a non-final variable combo inside an inner class
defined in a different method"
make global Combo read-only; simplify
merciless adding comments and renaming variables (not yet classes) to
make things clear
Checkbox "Plugin enabled"; Combo with global theme is restoring value
Heavy renaming