Better error checking, for example checking if the config is empty

Try to comply with freedb's: "Guidelines for optimal freedb support"
http://www.freedb.org/modules.php?name=Sections&sop=viewarticle&artid=38

Saving playlist

Make it possible for a program to in some way mark that
an entry is not coming from freedb, but created from the
program. Now it's not possible to know the difference, so
the revision of a new entry is always 1 instead of 0 as
it should be