Avoid box stuff leaking through for the color chooser
Support GtkStack and GtkStackSwitcher

These widgets are in GTK+ since 3.12, time that glade starts
supporting them.

https://bugzilla.gnome.org/show_bug.cgi?id=738480
Add editors for GtkStack and GtkStackSwitcher
Make stack switching work from the tree

This is identical to what glade is already doing for notebooks.
Support GtkSidebar as well
Many GtkStack fixes

Implement all of the required adaptor functions, add a virtual
'page' property and use it instead of visible-child-name to switch
between the pages to edit.
Set a title for new stack pages

This makes them show up in a connect stack switcher.
Stack switcher improvements

Mark the title property as translatable, and prevent the stack
property from showing up twice in the editor.
Adding 3.14 and 3.16 version targets to the GTK+ plugin

Updated GTK+ widget catalog for new properties and signals

Updated for GTK+ 3.14 and 3.16 (so far), this patch also modifies
the scrolled window editor to place the overlay-scrollbars property
nicely into the custom editor.

Also set GtkSidebar target version 3.16 (we dont encode odd numbers here)