Bug#785265: xserver-xorg was not installed

[John Talbut <jt@dpets.co.uk>]

In my case I had uninstalled xserver-xorg after the recent update, 
possibly because the description:

"This package depends on the full suite of the server and drivers for 
the X.Org X server. It does not provide the actual server itself."

suggested it was not required.  Clearly it is.  Reinstalled it and 
everything is working.

John