recsort sorts files found by photorec into directories based on the
extensions of the files.  Files are hard linked, so the original
recup_dir.* are left unchanged.

sortmp3dir will try to reconstruct filenames for each .mp3 file found
based on the ID3 tag.  It does make changes to the directory, but if you
run recsort first, then run sortmp3dir in the by_extension/mp3
directory, no changes will be made to the original recup_dir.*
directories.