To do this a few things needed to move into the os specific files, but the
overall change is fairly small and the difference on the Mac is amazing.
Subsurface now becomes a Mac app with Mac toolbar and useful default
fonts.
Changed the CFBundleIdentifier to be the reverse DNS of the subsurface
site (sadly, 'torvalds' is not yet a TLD).
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>