This API is much more flexible than the old, allowing any arbitrary set of chunks to be ticked.
These changes also improve the performance of random chunk ticking by almost entirely eliminating the cost of chunk selection. Ticking chunks are now reevaluated when a player moves, instead of every tick.
The system also does not attempt to check the same chunks twice, leading to further improvements.
Overall, the overhead of random chunk selection is reduced anywhere from 80-96%. In practice, this can offer a 5-10% performance gain for servers with sparsely distributed players.
I decided to scrap the max schema ID stuff, since it just adds extra places to forget updating. Instead, it's better to use minor version locks and version metadata, as we do for BedrockData and BedrockProtocol.
BlockPlaceEvent no longer extends BlockEvent, since it's now a multi-block event
getBlockReplaced() is removed
getTransaction() is added
to be honest, BlockPlaceEvent should be something like PlayerBlockPlaceEvent...
this simplifies usages of safe spawns, since the caller doesn't need to know which chunks will be needed for the spawn to be selected.
We'll need this in the future, because safe spawns may also get diverted horizontally as well as vertically, which might require loading adjacent chunks as well as the chunk the position is actually in.
in vanilla, it appears to behave as if the player always clicked on the up face if a block was replaced.
In PM, we were still using the original face, which caused bugs when, for example, placing a button next to a wall by clicking on the side of tallgrass. The button would replace the tallgrass, but stick to the wall, instead of placing itself on the ground like vanilla expects.
This may appear unusual to anyone who also happens to implement canBePlacedAt(), since the facing behaviour will be different. However, this behaviour appears to match vanilla, and even slabs (which I feared might break because of this change) work perfectly.
In the future, it may be desirable to pass some other value here, such as null, to indicate that the clicked block is being replaced. However, that's a BC break and therefore outside of the scope of a stable bug fix.
