This patch:
- Changes the behaviour of the colour pickers to trigger a reshuffle as soon as they're changed (rather than relying on the user to trigger it with the reshuffle button, by hide/showing a tag/artist, or switching the cloud type from tag to artist of vice-versa).
- Adds a better explanation for the tag scaling to the readme.
- Catches errors returned by the last.fm API when fetching artist or tag data.
- Changes the footer a bit.