[Banshee-List] [PATCH] ID3v2 Popularimeter (Ratings+Playcount) import/export

[Nick <nickbp gmail com>]

http://bugzilla.gnome.org/show_bug.cgi?id=532650

Background:

ID3v2 specifies a frame called "Popularimeter" (or POPM) which holds three
values:
1) A unique string which identifies the creator of the tag
       Examples: "Banshee" (used by this patch), "Windows Media Player 9
Series" (used by WMP and Vista's Windows Explorer), "no email" (used by
MediaMonkey)
2) A rating between 0-255 (0=unrated, 1=worst, 255=best)
3) A play count

This patch implements support for the Popularimeter field, giving Banshee the
following functionality:
- When a song using ID3v2 tagging is added to the library, its embedded rating
(if any) is also imported.
- When an ID3v2 song is rated, the rating is written to the song file. The user
must have "Write metadata to files" turned on for this to happen.