Pick the monitor most relevant to a rectangle more cleverly.

Pick the monitor most relevant to a rectangle more cleverly.

When monitors overlap (this happens with cloning), we were choosing a monitor
to associate with a window, for maximization for example, somewhat arbitrarily.

Now we have a more clever algorithm that considers the configured primary
monitor first, and that does not prefer monitors based on their sizes, but only
only how much of the window is in the monitor, excluding parts that were claimed
by another monitor already.