[mythtv] Allow mythtv-setup to use the downloadable icons from the new online database

[Matthew Wire]

I've been spending some time on the icon import stuff for mythtv and
have now produced some working patches which need wider testing.

See http://svn.mythtv.org/trac/ticket/3339 for more details and the two
patches (for libmyth and libmythtv).  Obviously you need to use the
latest ones.

Cheers,
Matthew


--------
The latest versions of these patches should now be fully working.



      * There's now an additional feature such that you can import an
        icon for a single channel by selecting it in the list and
        clicking "Icon Import".
        
      * Patch http://svn.mythtv.org/trac/ticket/4045 for videosource
        filter is included.
        
      * Another additional feature is that the channel selection dialog
        now remembers the last selected channel so you don't have to
        scroll up/down each time. This has appeared on the feature
        requests a few times.
        

I think all of the bugs are now fixed and this is ready for testing with
a view to merging.