Optionally recompute md5

[antifuchs]

The process of splitting the disc image into multiple tracks strips the MD5 metadata tag (because it is no longer valid if you chop up the data stream). We could recompute it, but the process requires decoding the audio, so would slow down operation quite a bit.

For archival purposes, it would certainly be nice to have. If someone wants to do this, be my guest!