Fix 'make check' after Gtk::Arrow has been deprecated

* demos/gtk-demo/example_headerbar.cc:
Use Gtk::Button::set_image_from_icon_name() instead of Gtk::Arrow.
* gtk/src/arrow.hg: Add #define GDK_DISABLE_DEPRECATION_WARNINGS in arrow.cc.
* gtk/src/filelist.am: Move arrow.hg to gtkmm_files_deprecated_hg.
Deprecate Gtk::Misc (almost) and Gtk::NumerableIcon

* gtk/src/filelist.am: Move numerableicon.hg to gtkmm_files_deprecated_hg.
* gtk/src/misc.hg: Deprecate, but only with comments. Can't be really
deprecated yet, because Misc is a base class of Label and Image.
* gtk/src/numerableicon.hg: Deprecate.