*: fixes - seeking is actually relative - added track IDs (yes these weren't implemented yet even though they're required), of the format /org/foobar2000/foobar2000/trackids/(hex encoded file path) - added playlist fetching for a possible implementation of the playlist protocol

This is a beefweb <-> mpris translation layer. Currently very unfinished,
and primarily serves as a method of getting mprisence to work with fb2k.

--paper <paper@tflc.us>