use MATE defaults for appearance-themes
Rename .desktop files to avoid file collision with Gnome2
appearance: Change also titlebar font if Metacity is running

Closes #40
https://github.com/mate-desktop/mate-control-center/issues/40
Fix some deprecations and remove some unused vars
Update POTFILES.* with renamed (mate-*) files
default applications: fix capplet name
Remove distro folder.
Merge pull request #79 from infirit/1.6

Cherrypick usefull commits from master