Correctly capitalize GNOME in the About dialog
Use double quotes in .ui file, which are more friendly to intltool

And also more consistent with the rest of the file.
Updated Spanish translation
Updated Czech translation
Updated Brazilian Portuguese translation
Updated Galician translations
Updated Danish translation
Updated Lithuanian translation
Updated Slovenian translation
Add a singleton for managing xsettings overrides

https://bugzilla.gnome.org/show_bug.cgi?id=705359
UI changes, new categorization of the tweaks
some tweaks were moved to the tweak_legacy.py file
tweak_legacy.py is loaded with the  -l command line option.
Notifications with the logout option
using GDBus for the logout
using a GtkStack to store/show/hide the tweaks of each category
The GtkStack can not be homogeneous
Single instance of gnome tweak tool
the search works
some changes