Add back xrender

[Redo11]

A lot of people liked it and used it, opengl still got some quirks sometimes, Xrender is nice fallback. Also xrender is only backend fully supporting 2+ cursors with xinput. I doubt 2+ cursors are going to be implemented into opengl and definitely not with wayland. Xrender, even if buggy and unmaintained is the only way to fix this. Also it's way more slim and doesn't use hardware acceleration that much.