Add GTypeClass methods as Python GObject class methods

Take all the methods from an objects type classs and add them
as class methods. For instance, GObject.ObjectClass.list_properties
is available as GObject.Object.list_properties().

Co-Authored-By: Simon Feltman <sfeltman@src.gnome.org>

https://bugzilla.gnome.org/show_bug.cgi?id=685218