An update to the last version, including everything I mentioned (minus one thing).
-Song history, which is currently set to 25 songs forward or 25 songs backward before generating a new set of 50 songs; this should have an average better time between song changes, mimicking what gapless playback should be.
-A previous button, so you can go back if you forgot to hit the repeat button or want to download a song.
-Song downloading! Complete with automatic artist/song name/album art metadata tagging.
Minor bugfixes for other stuff. Lists from the commandline should work now. In addition, the internal list has been updated to have my most recent additions.
Note: Keyboard controls were not implemented due to a strange bug with using FXML to handle events. When event chains are generated, they are for some reason not chained with the root of the FXML hierarchy, which means that due to the dynamic nature of the controller, I am unable to have keyboard controls work, at all.