Updated Czech translation
Updated Czech translation
Updated Greek translation
Updated Slovenian translation
Updated Swedish translation
[l10n] Update Catalan translation
[l10n] Update Catalan translation
appdata: update license metadata
Require GTK+ 3.12

For GTK_DIALOG_USE_HEADER_BAR
Use a header bar on the preferences dialog
Preferences dialog: make non-modal
Updated Czech translation
Rename app to window

Prep for GtkApplication
Remove useless function set_game_graphics()
Remove command line options, port to GApplication

Both of the meaningful command line options have been broken for a long
time, and their value appears limited.
Updated Spanish Translation
appdata: fix spelling of metadata-license tag
Updated Brazilian Portuguese translation
Add missing cast
Fix restoring hotkeys to default

This button did not do anything. Alas.