noop, simplify code.

(!mixer || !editor) are checked at the top of the funtion
and also used without checks further down.
more color work, including removing rgba{_p_}_from_style()
change GTK rc file system to use just a single file, which is color-neutral.

* packaging scripts need modification
* light theme file left in place to help with possible generation of alternate theme
change packaging of GTK rc file for OS X and Linux.

I cannot find the equivalent location for Windows
lots more color work, closer and closer to being ready for ... being taken apart again
another metric ton of color work
more tweaking of color management.

User's own modification to NAME.colors are stored in $CONFIG/my-NAME.colors now.
remove debug output
install single color theme file during waf install
correct install location for .mo files (i18n) and cleanup LOCALEDIR use a bit
add DEBUG::Butler and use it
remove superfluous PBD/ARDOUR:: init calls

this reverts 339670b
fix meter scale colors (meterbridge)
more DEBUG::Butler output, formatting corrections, and a warning on cerr if capture/playback buffers are too full/empty
add set-session-extents-from-edit-range
update_time_selection_display should work when in smart mode
add DEBUG_THREAD_SELF to allow use of DEBUG_TRACE with thread IDs on both normal pthreads platforms and PTW32
use correct conditional to choose between different DEBUG_THREAD_SELF macros
add sndfile I/O test application, used for testing disk bandwidth for writing audio files
remove unnecessary sleep