This is a major change to the way block metadata is handled within the PM core. This separates variant metadata (which really ought to be part of the ID) from state metadata, and in a couple of cases flattens separate states of blocks together.
The result of this is that invalid variants can be much more easily detected, and additionally state handling is much cleaner since meta is only needed at the serialize layer instead of throughout the code.
This now computes BBs relative to 0,0,0 and then offsets them as appropriate. This requires less boilerplate code and also furthers the goal of separating block types from instances.
This allows the removal of lots of ugly code, and also exposes lots of similarities with how this update type was handled. This can be further improved in the future to more generically handle cases.
I realized in the process of changing this, that it might actually be simpler to treat to treat scheduled updates and neighbour updates as one and the same. They use the same mechanism for being saved on chunks (TileTicks),
and doing that would make updating only require one queue instead of two.
RedstoneOre: use onActivate() to trigger glowing
this is not technically correct behaviour, but this preserves the current behaviour.
