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.
mushroom stem (and all-sided stem) are unique blocks, which don't drop anything and which don't stack with other shroom variants when block-picked.
They also get mapped to the same block when placed, and there's no distinction between red mushroom stem and brown mushroom stem.
Now, blocks do not respond to silk touch unless specifically opted into. Since this always involves custom drops in one way or another, it's easy enough to figure out which blocks need to be marked for silk touch - anything that overrides getDrops, getDropsForCompatibleTool or getSilkTouchDrops is a block which _might_ need to be flagged. Using these criteria to reduce the number of blocks needing to be checked, I was able to manually invert the behaviour as needed.
This fixes reoccurring bugs with blocks erroneously dropping themselves whenever new blocks are added and someone forgot to set that flag, granting players access to internal blocks with strange behaviour.
