configure gtk settings gtk-dialogs-use-header and gtk-enable-animations
Bump version to 1.9.3
Update gtk-dialogs-use-header key default to false

To stay as close to the Gtk+2 UI as possible.
We toggle in mate-settings-daemon now.
Also remove from EXTRA_DIST
lockdown: Move disable-log-out key here from mate-panel

To be used in more places like mate-session.
mate-about: Add Google Summer of Code students
mate-about: Add MATE Slackware maintainers
Sync translations with transifex
Merge remote-tracking branch 'upstream/master'

Conflicts:
	schemas/org.mate.interface.gschema.xml.in.in