Fix fullscreen toggle shortcut

Remove the "Meta" modifier so that the shortcut works on Windows.
On the Max OSX, the standard key for full screen is "CTRL+COMMAND+F" so for the mac, that's what we want, which is what this does, [on mac/Qt: META=CTRL, CTRL=COMMAND]. So, we need to put this in a #ifdef if you want to make this change for windows.