[mpris] suggested additions to the MPRIS spec

[Ian Monroe]

First off Dragon Player http://dragonplayer.org now implements all of
the / and /Player parts of the MPRIS spec. It does not do /TrackList
since it has no playlist. Could perhaps we put a note in the spec
supporting this subset officially? Mostly just to let client writers
know they should check for TrackList existence before assuming its
there.

I added a 'load' method to /Player. It plays the given URL
immediately. For other players, this could be done with a combination
of TrackList commands, but it's still handy. Its obviously essential
for TrackList-less players. Could this be part of official spec as
well?

Talking to funman, he mentioned it would make sense to have in the /
root module, a method to return the version of the spec being
implemented. For instance the current spec could be version 1.0. With
the addition of the load method, that would be 1.1. We would only have
a major version change (2.0) when backwards compatibility is broken by
removing methods or changing method signatures (probably something we
shouldn't ever do). Such a method would be common-sense
future-proofing.

Thanks,
Ian