now that the colour and skull type are included in the block type data, it's no longer necessary to maintain shim items to retain this information in the item data.
before anyone starts screaming:
1) it's easy to create your own wrapper that converts items to arrays
2) there is no longer a single standard way to encode items.
3) the way that item serialization now works requires an ItemSerializer, which, barring singleton use, must be dependency-injected. Since there's no way to inject dependencies into jsonSerialize(), this means that its behaviour cannot be customized.
this allows plugins to add their own mappings (though they should really be using StringToItemParser) without needing any legacy numeric ID bullshit in the mix.
This commit completely revamps the way that blocks are represented in memory at runtime.
Instead of being represented by legacy Mojang block IDs and metadata, which are dated, limited and unchangeable, we now use custom PM block IDs, which are generated from VanillaBlocks.
This means we have full control of how they are assigned, which opens the doors to finally addressing inconsistencies like glazed terracotta, stripped logs handling, etc.
To represent state, BlockDataReader and BlockDataWriter have been introduced, and are used by blocks with state information to pack said information into a binary form that can be stored on a chunk at runtime.
Conceptually it's pretty similar to legacy metadata, but the actual format shares no resemblance whatsoever to legacy metadata, and is fully controlled by PM.
This means that the 'state data' may change in serialization format at any time, so it should **NOT** be stored on disk or in a config.
In the future, this will be improved using more auto-generated code and attributes, instead of hand-baked decodeState() and encodeState(). For now, this opens the gateway to a significant expansion of features.
It's not ideal, but it's a big step forwards.
