[git-p4: depot-paths = "//depot/": change = 1578]

optional items are available at the Object level now... so we can
make these a lot more generic...  not so much specific code anymore..
(though some clients, such as MediaControler, will only use these
elements if ContentDirectory v1 listed them, such as
originalTrackNumber on a MusicTrack)...

add cdrtoc.py that parses toc files that include title and other
information..

add an attribute to flac that has the tags...  This makes it
more generic...

use the new toc parser and the tags element to set the title on
tracks...

also set the original track number..

[git-p4: depot-paths = "//depot/": change = 1577]