Make sure to reset all the GSource timer ids

Avoids warnings like 'Source ID 8382 was not found when attempting to
remove it'. In particular some removals were missing in menuframe.c
resulting in a warning being printed every time a submenu was opened.
Move final frame adjust in flashing to timeout func

This possibly avoids badness when the timeout destroy notify is removed
from the frame release func.
Allow selecting menu entries during menuHideDelay if you click again, bug 5501
Only add xqueue listener fd once, bug 6326
Remove wrong code from button mask loading code, bug 6065

The READ_MASK_COPY macro already uses these exact fallbacks, so these
lines just overwrote the custom bitmaps with the default fallback bitmaps.
Make theme.c indentation more locally consistent

Also removes some comments that is just the code with s/_/ /g
Reduce length of theme.c a bit