[gtkmm] Created tag 3.21.3

[Murray Cumming <murrayc src gnome org>]

The unsigned tag '3.21.3' was created.

Tagger: Murray Cumming <murrayc murrayc com>
Date: Mon Jun 27 11:02:46 2016 +0200

    3.21.3

Changes since the last tag '3.21.2':

Chun-wei Fan (1):
      Visual Studio builds: Update gdkmm project

Kjell Ahlstedt (8):
      Gtk::SizeGroup: Deprecate set/get/property_ignore_hidden()
      tools/gen_scripts: Exclude gdkinternals.h from the .defs files
      Gtk::RecentManager, TreeModel: Add _IGNORE() directives
      gdk: Regenerate docs.xml and .defs files
      Add Gdk::DrawingContext
      Gdk::Window, Gtk::Widget: Deprecate and add
      Gtk::AppChooserDialog, FontChooserDialog: Add _UNMANAGEABLE
      Gtk::ScrolledWindow: Deprecate remove_with_viewport()

Murray Cumming (1):
      3.21.3