klomp-db: pull readLibMetadata to a sub, generalize column parsing
klomp-db: validate song path a little
klomp-db: use 'find -iname a -or -iname b' instead of messy 'find -iregex="a|b"'
klomp-db: modify find results in place
klomp-db: add md5sum column
klomp-db: split addSongs() => (addSong, getSongRow, getSongInsertStmt, getSongDeleteStmt)
klomp-db: thread add songs
klomp-db: use filesize/mtime instead of md5sum to skip songs
klomp-db: small fixup
klomp-db: add acoustid track ID
klomp-db: refactor threads
klomp-db: fail if database does not exist
klomp-db: pull is-thread-running to a sub
klomp-db: restrict threads to 1 if threading is disabled
klomp-db: ignore STDERR on acoustid-track-fetch