Fix abort signal when focuser ends at original position, improve tests.
This MR improves Focus tests to try to spot more issues. One is the abort signal not being emitted when the (absolute) Focuser ends at the same position as it was before the autofocus procedure.
This MR also introduces the KTELL macro helper, which creates a systray icon and posts notifications about the progress of the test.
Focus tests are expected to pass at 100%. Do not merge if they don't.