Consider switching to an actively maintained X server

Since freedesktop.org is badmouthing X11 and is preventing X.Org from being actively developed, we should switch to an X server that is actively maintained and has a positive attitude to supporting X11 as soon as possible ("possible" = available in FreeBSD Quarterly Packages).

Candidates:
* **XLibre**, an actively maintained fork of X.Org - https://github.com/b-aaz/xlibre-ports
* **wayback**, a modern X server which is using Wayland as its hardware abstraction layer: https://github.com/kaniini/wayback

In any case, we need the software in FreeBSD Ports and quarterly Packages so that we can adopt it.