Log Message:
Update audio/py-mutagen to 1.20

1.20 - 2010.08.04
 * ASF: Don't store blocks over 64K in the MetadataObject block;
   use the MetadataLibraryBlock instead. (#60, Luká# Lalinský)
 * ID3: Faster parsing of files with lots of padding. (#65, Christoph Reiter)
 * FLAC: Correct check for audio data start. (#67)