Refactor the entity protocol

[IntegratedQuantum]

Using a zon array for everything is no longer the great solution it once appeared to be:

• The null separator between entities and item drops is kind of weird and no longer needed since
• item drop updates are sent one by one, completely separate from regular entity updates.
• Using zon to encode 16 bit integers when removing item drops is a really inefficient.
• zon really only makes sense for the item date, everything else can be stored more efficiently in numbers directly.