gtk+-2.0, gtk+-3.0: port lots of annotations from the GIR version
gtk+-3.0: Add type_ids and abstract annotations for classes
gtk+-3.0: port "struct" annotations from the GIR version
gtk+-2.0, gtk+-3.0: Hide non-public symbols
gtk+-2.0: port "struct" annotations from the GIR version
gtk+-2.0, gtk+-3.0: port more annotations from the GIR version
gtk+-2.0, gtk+-3.0: more various fixes
gtk+-2.0, gtk+-3.0: Make Widget.get/set_parent compatible with its property
gtk+-2.0, gtk+-3.0: Radio/ActionCallback are only vala-helper types
gtk+-2.0, gtk+-3.0: Gtk.get_default_language is unowned
gtk+-2.0, gtk+-3.0: GtkCssProviderError/GtkPrintError are errordomains
gtk+-2.0, gtk+-3.0: Fix gtk_target_list_find
Test error type check
Make sure type check expression has valid type

Fixes bug 696729