The other elements are not that interesting now that we're
using pangocairo in the pango plugin, and should probably
just be removed.

https://bugzilla.gnome.org/show_bug.cgi?id=687520

Allows applications to connect to the "draw" signal of
the element and do their custom drawing there.
Includes an example application demonstrating usage.

Fixes: https://bugzilla.gnome.org/show_bug.cgi?id=595520