Empty the database cache.
The database stores the details of artists, albums and tracks that have been downloaded from MusicBrainz and songs that have previously been loaded into Jaikoz.
This allows subsequent lookup to be done locally and much more quickly, but we may wish to empty the cache to ensure that Jaikoz gets any updates to MusicBrainz since the information was originally downloaded.
It also speeds up the reloading of files into Jaikoz from our computer.