Remember recent entries in the playlist editor

[RocketMan]

As a DJ entering a playlist in real time, when I manually enter a non-zookeeper album (that is, an album where I must key in the artist, album, track, and label name), I would like for zookeeper to remember the most recently entered values for artist, album, and label.

Sometimes I play multiple tracks from the same album, and this will avoid my having to type in all of the information multiple times.

[Note, this is a regression, as earlier versions of the playlist editor remembered this information.]