Merge pull request #29 from infirit/master

Various fixes/cleanups for tests and autofoo
Add GTK3 support in configure
Fix m4 path
Configure: Improve GTK3 support
Add GTK3 support
copy-theme-dialog: Add GTK3 support
mate-screensaver-dialog: Add GTK3 support and fix GLIB deprecations
mate-screensaver-command: Fix glib deprecation
mate-screensaver-preferences: Add GTK3 support
test-fade: Add GTK3 support
savers: Add GTK3 support
floaters: Add GTK3 support
popsquares: Add GTK3 support
savers: Add GTK3 support
Re add removed variable for GTK2
Add theme to use GNOME foot logo as floaters screensaver
Fix --with-libgl config option