In the future, McRegion and PMAnvil will become deprecated legacy formats which we won't support for writing anymore. However, this brings complications because Anvil (which would not be deprecated) would be sandwiched between its deprecated base (McRegion) and its deprecated child (PMAnvil), complicating the implementation (particularly for PMAnvil).
This abstracts away the generic Region-based world functionality into a separate class, making McRegion, Anvil and PMAnvil all inherit from it directly. Since only the chunk formats are different, they are more accurately siblings rather than parent-child (although Anvil and PMAnvil are cousins, ish).
The cause of this was the flow decay of falling water changing, but the flow decay is ignored for falling water. This caused the block to be repeatedly set to itself, triggering local block updates, causing the disease to spread in large falling water bodies and cause immense amounts of lag.
this parameter was previously used to send blocks with a different set of flags, immediately, to players. However, the flags have been demonstrated useless and the direct sending is pointless now since packets are buffered now per session, so we might as well take advantage of the batched block update sending.
These flags are not intended for network use, instead they are supposed to be used internally by the game. For network, we only need to care about the 0x02 flag (send to players) because that's necessary for the client to render the block.
readline on Windows causes issues with console output corruption. Additionally, PM readline impl is extremely buggy and probably ought to be removed. However, have a hotfix for now.
This is only implemented in 1 place where the collision box should just be zero anyway, so there's no point this existing.
There's a lot of other blocks which should have bounding boxes without collision boxes as well, but that's outside the scope of this commit.
this will be necessary to deal with negative IDs (if I choose to do that), and it'll also be necessary if I decide to do any shift hacks to merge ID/variant for block IDs, because we don't want such things to affect items before we're ready to deal with that.
