Add maximized placement mode

Submitted by Rob McCathie

Assigned to Olivier Fourdan @olivier

Please consider adding another selectable placement mode, one for maximizing all new windows.

I'd suggest that it runs the routine for center placement (for setting where the window will be ifthe user unmaximizes it) and then maximizes it.

I can think of a few use cases. For me personally it's smalls screens - my netbook.