Window offscreen detection and mitigation.

[blakepell]

Now that the client can save the last window position and restore it as a setting, add code that will try to detect if the Window is off the bounds of all monitors (and move it into a visible position if that's the case).

This could come about because of changes in resolution (or because it was moved off of the screen).

[blakepell]

https://stackoverflow.com/questions/37927011/in-wpf-how-to-shift-a-window-onto-the-screen-if-it-is-off-the-screen