Add remove-apple-cruft-files and treat :2eDS_Store as an apple cruft file
trigger a GC when copying tags, otherwise we were running out of memory.

 * this is probably a bogus hack that we shouldn't need, but it seems
   to make things work better for now. It would be nice if we didn't
   need this.
export some file handling functions

 * is-file-p, recursively-list-files, apple-cruft-file-p, remove-apple-cruft-files
add transcode.asd
add flac tag conversion routines