[gtkmm] Created tag 3.21.6

[Murray Cumming <murrayc src gnome org>]

The unsigned tag '3.21.6' was created.

Tagger: Murray Cumming <murrayc murrayc com>
Date: Wed Sep 14 10:13:50 2016 +0200

    3.21.6

Changes since the last tag '3.21.4':

Kjell Ahlstedt (9):
      Gdk: Regenerate docs.xml and the .defs files
      Wrap enum GdkAnchorHints
      Gtk: Regenerate docs.xml and the .defs files
      Gtk::FileChooser, Menu, ScrolledWindow: Wrap new methods
      Regenerate gtk_signals.defs
      Add the Gtk::ShortcutLabel widget
      Gtk::RadioMenuItem, RadioToolButton: Add join_group()
      Gtk::Clipboard::wait_for_uris(): Fix the documentation
      Gtk::TreeNodeChildren: Deprecate the reverse iterator

Murray Cumming (11):
      Tiny whitespace change.
      Regenerate GTK+ .defs.
      Popover: Add popup() and popupdown().
      Regenerate gdk .defs.
      Regenerate gtk .defs.
      Regenerate *docs.xml files.
      Pixbuf: Add set_option() and remove_option().
      Gdk::Pixbuf: Add copy_options().
      Gdk::PixbufFormat: Added is_save_option_supported().
      ScrolledWindow: Added get/set_propagate_natural_height/width().
      3.21.6