When binding a boolean setting to a boolean property, invert the values.
This avoids the requirement for writing a pair of mapping functions for
this extremely common case.
Add a test.
https://bugzilla.gnome.org/show_bug.cgi?id=625833
Add a <flags> tag to the schema file format and a flags='' attribute to
go along with. Add some extra test cases for those.
Add new g_settings_{get,set}_flags() calls and support binding to
GParamSpecFlags properties. Add test cases.