Remove useless checks for Yelp
Rename mvc-helpers.{c,h} -> gvc-utils.{c,h}
Move some files and directories to better locations

- mate-volume-control/data changed to /data
- mate-volume-control/src/* moved to mate-volume-control
- sound-theme/sounds changed to /data/sounds
- sound-theme/*.{c,h} moved to mate-volume-control
- Removed AUTHORS and ChangeLog.pre-2-26 from mate-volume-control
Remove unused parts of Makefiles and clean up tabs