Wrapper function around Screen('OpenWindow') and Screen('CloseWindow')

[shippy]

There are a couple of tasks that are always necessary to do with Screen('OpenWindow'); most prominently, it sets the windowPtr and screenDims in settings.device. This should be factored out for general ease of usage, and for preventing some simple errors.

What simple errors? For example, almost all scripts use screen.device.screenDims(3:4) as width and height. But this is only correct as long as the top-left pixel of PTB's screen is (0, 0)! The actual width and height are [dims(3) - dims(1), dims(4) - dims(2)].

Screen('CloseWindow') doesn't present many problems, but having a shutdown script that unsets relevant settings.device values would be a good complement.