Development continued there for a while. Now I will remove it
and used the toolkit implementation instead.
Changes:
* Retry faster
* Handle GLib errors
* Don't always dump the tree
* Support master atspi api
The uitree module exposes the at-spi tree. We can use it to do
functional tests of the UI, by checking if the expected
widgets exists, clicking them etc.
A simple example of how this can be used is in the test, which
runs a window and check that it has the expected button.