This adds clip area, accessible role, mapped, realize, is-toplevel, child-visible, mnemonic labels and tick callbacks to the displayed information.
https://bugzilla.gnome.org/show_bug.cgi?id=736191
Tools like damn-lies rely on being able to generate .pot files from pristine checkouts, so everything that goes into the .pot file has to be in git. This is not ideal, but we already do the same for other .ui.h files in GTK+.
