Add a set of helper functions and classes providing functionality
for dumping widget/window hierarchies and logging events. They
can be used by including a .pri file for diagnosing bugs and
comparing Qt 5 to Qt 4.

Change-Id: I0206f8e57b02540cd80a3e9446c894023d442ddc
Reviewed-by: Andy Shaw <andy.shaw@digia.com>
Reviewed-by: Shawn Rutledge <shawn.rutledge@digia.com>