Split from #212: support applications which request that we unmaximize them.
I am not quite sure how this is supposed to work, and we don't really care too much about it: the user can unmaximize client side using the operating system's window controls.
r8294 fixes the test application, removes some crappy code that was added as a workaround for the buggy test class, and now correctly supports the add / remove / toggle modes.
r8295 synchronizes the client and server side maximized state.
Can be tested using the "test window maximize" test application. We now also show the window as maximized via "xpra info" when it has been maximized by the client (this was not the case previously).
Still works wonderfully.
this ticket has been moved to: https://github.com/Xpra-org/xpra/issues/537