The delete() method on Mutagen objects writes the file directly. Calling
save() was unnecessary and, in at least one case we found, could inadvertently
preserve non-standard tags that Mutagen did not understand.
* Adds support for importing/managing .wma and .asf files
* Adds support for all available ASF tag equivalents
* Adds two utility methods for (un)packing embedded ASF pictures
* Modifies scrub plugin to work around the lack of a delete method on
ASFTags object.
This is the first of several commits that will modernize the beets codebase for
Python 2.6 conventions. (Compatibility with Python 2.5 is hereby abandoned.)
