add some infra to be able to get and set device properties (as well
as know if devices changed to we can refersh a gui or re-apply saved
settings etc.). it doesn't do everything but... it adds enough to
build on in e.
as per mailing list discussion about dropping xcb support now. it
hasn't been complete for a long time, thus not recommented for being
turned on. as we are moving to a wayland world xcbmakes even less
sense. as agreed, time to clean up a bit and remove a distraction as
well as not well tested code. this also updates po's too.
@feature