docs: Link from tracks_with_metadata to PlaylistTrack
docs: Add docstring to PlaylistContainer.owner
plcont: Add reorder_tracks()
error: Rename Error to LibError, add new Error superclass
error: Make Timeout a subclass for Error
error: Update docstring
playlist: Replace improper ValueError use with spotify.Error
inbox: Add InboxPostResult class with error property
session: Add inbox_post_tracks()
docs: Update dev status
inbox: Link to Session.inbox_post_tracks()
session: Specify tracks can be a single Track
docs: Explain play arg to play()
docs: Explain where to find the OfflineSyncStatus
docs: Explain where AudioFormat is used
docs: Make the class with the link attribute visible
docs: Mark links as attrs, not methods
docs: Fix wording for update_subscribers()
Require cffi 0.7 so we can use new_handle()/from_handle()
image: Use ffi.new_handle() for callback userdata