Print dialog backends

["John (J5) Palmieri" <johnp redhat com>]

I finally got the CUPS backend to successfully make non-threaded async
calls and am going to concentrate on integrating what I have been doing
with Alex's work so far.  I wanted to give an brief overview of how I
see the backends working and get some feedback.

I basically have an interface EggPrintBackendIface which will provide a
way for doing basic things like getting a list of printers and getting
notifications on status changes and the like.  It will also provide the
interface for managing print jobs.  The idea would be for the
PrintDialog to return a backend and printer name to the higher level API
which would then use the backend to send the job to the printer.  Other
applications such as eggcups would also be able to use the backends to
monitor the progress of print jobs and provide the interface for
canceling them.

I am building the cups backend as the model and will also write a print
to file backend.  Other interesting backends could involve e-mail or
faxing but I'll leave those up to other people.

-- 
John (J5) Palmieri <johnp redhat com>