#30 Improve multiple monitor support

[Slugsie]

PySol FE is generally fine on a multi monitor system, but a couple of improvements would make it so much better:

1. It should remember which monitor it was on when it closed. Currently I would typically play PySol on my right hand monitor with something else on the primary monitor. I can move PySol no problems, and it works. But when I close and restart it's back to the main monitor again.

2. Any popup dialog boxes appear on the main monitor no matter where the game is running. It's frustrating to go and find the dialog. It should always appear dead centre of the primary window irrespective of the monitor it's running on.