AttackFM 0.5.4

• The AttackFM folder is now a record collection: cached songs file themselves into Artist/Album folders instead of one flat list, and empty shelves fold away when their last song leaves. Existing caches sort themselves onto their shelves on the next cache pass.
• (from 0.5.3) Readable filenames, instant adoption of the browsable folder on grant, offline art and Canvas from the on-device cache.