Revert "Rerender on button press only when focus changes"

This reverts commit b714878f52ef7c175699ed831c5925a577621f5a.

That commit introduced a regression: clicking on floating windows would
no longer raise them reliably.

fixes #1260
handle windows whose WM_TRANSIENT_FOR points to themselve

I consider this behavior broken and not respecting the standard, but it
happens in real life, and it’s better for i3 to not busy-loop in such a
situation :).

fixes #1259