Add MP4 storage style for bools
Simplify MP4 bool storage
Genre lists for MP4 files
List decorator gives single decorator
Abstract ListStorageStyle
Serialize converts None
Genre list tests for more formats
Add mediafile art test
Add StorageStyle for mp3 images
Add storage style for MP4 images
Image storage style have bytearray type
MP4 only supports png and jpeg images
Add storage style for vorbis images