Texture and Icons fine-tunning
Attempt at fixi9ng lighting bugs
Max offers config added

Added hard-coded limit of offers as a constant.
Redstone and texture updates (comparator)

Jukebox now can be powered from anywhere, not only below. It only
transmits power to a Redstone Comparator and the signal strength is the
current active slot (1 to 8). When a slot changes, the comparator
updates.