Clean up maximization and un-maximization logic

Clean up maximization and un-maximization logic

We should not try to un-maximize the windows from inside
the function wMaximizeWindow(), as that makes no sense.

If the window is already maximized then we don't call
wMaximizeWindow() anymore and call wUnmaximizeWindow()
instead, which will use the old geometry regardless
of which maximization is active (horizontal, vertical,
maximus, etc). And the old geometry now is also saved
when we enter wMaximizeWindow().

So when we call wMaximizeWindow() or wUnmaximizeWindow()
we really mean "maximize to the specified state" or
"go back to whatever old geometry coordinates we had before".