TODO file:
----------

* Add a callback to the track and file scanning functions and 
  bump library interface.

* Modify LIBMTP_device_entry_struct to contain a field for "flags"
  which can be used to identify different special device 
  characteristics (bugs...) on certain devices. Also add "flags"
  to device struct, so that it remains easily accessible for the
  session, and bump library interface.

* SPEED: File chunk size (ptp.c) increase to good size.

* SPEED: Cache the supported object properties at first read/startup.

* SPEED: use the enhanced functions to get all props for one object
  in a single go!

* Make abstract playlists really become size -1 when created as 
  the ones created on the device instead of the current 1 byte size.
  (Is this even possible?)

* Support abstract MTP album (0xBA03) just like playlists. Too
  bad that Creative Zen Micro do not support them, they group the
  albums by using the metadata instead. Support representative
  sample (i.e. album cover).

* Support playback and volume setting on devices that have it.
  (I don't have one that does - Linus.)

* Make an API that can return several devices not just connect to the
  first one...