Remove randr 1.1 support in xfce4-display-settings?

[Nick Schermer]

> The code is already available on git.xfce.org, in the
> 'xrandr-display-settings' branch of xfce4-settings (not merged into
> master yet). You can get it and build it, it should work; it's not
> widely tested though, no more than three or four people afaik…

If this is already better then in master I have no problems merging
the code so we can give it some wider testing (IIRC it is not broken
or has any regressions compared to 4.6). Once Jerome finished his
widget we can push a development release.

Nick