GUI test about box.

Added new helper functions to simplify testing of modal
dialogs like the about boxes.

Added test that opens the about box via the help menu,
verifies it opened and then dismisses it with escape.
Add about qt dialog GUI test.

Refined helpers for testing modal widgets
by actually restricting them to modals instead
of any active window.

Added test that opens and closes the Qt about
dialog via the menu and dismisses it much like
the other about box test.

For some reason the - disfunctional anyways - attempt
to clean up self.app during tearDown left the application
in a bad state when called after using a modal widget
which prevented the tests from ever opening a blocking
modal widget after that. Removed this call from tearDown.
Improve test execution speed by removing cargo culted delays.

As the vast majority of our GUI tests aren't relying on an event
loop there is really no need to wait for anything. I only added them
because I saw them in sample test code. Remove all delays not relying
on something happening asynchronously in an event loop and reduce the
delay for the ones that do. This should help our GUI tests scale in
the future as we add more of them.