Recommendation is to avoid using the year nomenclature as this
information is already encoded in the git repo. Avoids needing to
repeatly update.
Also updates AUTHORS.txt from current repo with contributor names
Also removes the return value from the BITMAP_STORE's themeChanged
method as it will provide the wrong answer for the second frame it's
called on.
Also hooked up ACTION_TOOLBAR, the app launcher, and the project tree
to the wx event for system color changes so they change on the fly.
Fixes https://gitlab.com/kicad/code/kicad/issues/6026