Gtk::Widget: Undeprecate reparent()

* gtk/src/widget.[hg|ccg]: Undeprecate reparent() and implement it without
calling the deprecated gtk_widget_reparent().
Gtk::Builder: Fix ref count in get_widget() and get_widget_derived()

* gtk/src/builder.[hg|ccg]: get_widget() and get_widget_derived() shall not
add a reference to the fetched widget. Bug #731444.
Add test case tests/builder

* tests/Makefile.am: Add builder/main.cc.
* tests/builder/main.cc: New file. Bug #731444.
Gtk::Builder: Add more documentation

* gtk/src/builder.hg: Copy some documentation from GtkBuilder, describing
the lifetime of windows, other widgets and other objects. Bug #731444.
Wrap GtkOverlay widget

	* Create gtk/src/overlay.{hg,ccg}
	* Update gtk/src/filelist.am
	* Add "get-child-position" signal to gtk/src/gtk_signals.defs
	* Add GTK_TYPE_OVERLAY to
	tools/extra_defs_gen/generate_defs_gtk.cc
	* Add overlay.h to gtkmm.h
demo: Add Overlay demo

	* Add demos/gtk-demo/example_overlay.cc
	* Update demos/gtk-demo/demos.h
	* Update demos/Makefile.am
IconInfo: Deprecate some methods.

* gtk/src/iconinfo.hg: Deprecate set_raw_coordinates(),
  get_embedded_rect(), get_attach_points() and
  get_display_name(), using the mostly useless deprecation comments
  from GTK+:
  https://git.gnome.org/browse/gtk+/commit/gtk/gtkicontheme.c?id=84bc9bba4214ac4dc05cb029b45bffbb84fa1393
WidgetPath: Deprecate regions methods.

* gtk/src/widgetpath.hg: Deprecate iter_add_region(),
  iter_remove_region(), iter_clear_regions(), iter_list_regions()
  and iter_has_region() using the rather useless deprecation
  comments from GTK+:
  https://git.gnome.org/browse/gtk+/commit/gtk/gtkwidgetpath.c?id=93b31790424cbc2face0a885b5dd49889c2f297e
Regenerated GDK .defs.
Regenerate gtk .defs.
demo: Avoid use of deprecated API.

* demos/gtk-demo/example_icontheme.cc: Remove the code and UI that
  deals with icons' display names.
Update *_docs.xml files, used to generate documentation.
Merge branch 'master' of git://git.gnome.org/gtkmm