Tweak quick tile shortcut combination algorithm
This attempts to provide a compromise between the old and the new quick tiling behavior.
With the proposed changes, if a window is tiled so it occupies the left half of the screen and Meta+Right is pressed, the window will occupy the right half of the screen. Quarter tiled windows are tiled as before. If the window is migrated to another screen, it won't be untiled.
Currently, if you press Meta+Up several times and there is no output higher, you are going to see the following:
- on the first Meta+Up, the window will be tiled so it occupies the top half of the screen
- on the second Meta+Up, the window will be untiled
This behavior is unexpected, and it looks confusing when you have a window that's tiled in the top left screen quadrant and press Meta+Up.