Tick Handler Changes

1. Renamed CommonTickHandler to ServerTickHandler. Given that it only
handles server ticks, this seems like a reasonable name. Also changed
its profiler label to the new name.
2. Deleted ClientTickHandler and removed any references to it in
mod_pocketDim. It was never used for anything.
Reorganized Tick Receivers

1. Reorganized our code to initialize tick receivers each time the
server starts rather than once when the mod is initialized. This is
needed because reusing a single instance of each class across different
single-player sessions could cause scheduled events for one world to
leak into another world. This approach ensures that we discard all
pending events.
2. Separated the implementation of Limbo decay from a tick receiver that
periodically triggers fast decay. All of the decay code has been kept in
LimboDecay, while the ticking is handled by LimboDecayScheduler. This
change separates some functionality that should be independent, but
also, it's needed so that BlockLimbo can have access to LimboDecay's
methods without holding on to a tick receiver instance.
3. Minor change: renamed ChunkLoaderHelper.loadChunkForcedWorlds() to
loadForcedChunkWorlds().
Minor Changes to NewDimData

Made some minor changes to NewDimData. Fixed some comments for the rift
search functions that incorrectly indicated the search would not detect
rifts adjacent to the center of the search range. That behavior changed
some time ago. Also added an unused field called "chunkMapping" for
associating chunks with lists of links. It'll be used for implementing
queuing of rift regeneration when chunks load.
Implemented Chunk-Links Mapping

Implemented support for tracking the list of links in each chunk in a
dimension. This will be used for scheduling rift regeneration when
chunks load.
Minor Change

Rewrote the NewDimData.deleteLink() version that would accept x, y, and
z as parameters. There was some redundant code for getting the
parameters from a Point4D instance just to create another one to find
the target link. Now we pass the source point in directly.
Minor Changes

Minor changes to DimLink to simplify DimLink.getDestinationOrientation()
and to clarify the output of DimLink.toString() when no destination is
available.
Implemented Scheduled Rift Regeneration

1. Implemented scheduled rift regeneration in RiftRegenerator. The
previous randomized selection algorithm has been removed completely. All
regeneration is scheduled now. We perform numerous checks to make sure
that regenerating a rift is safe.
2. Removed FastRiftRegenerator as RiftRegenerator performs roughly the
same task but with more flexibility. Updated TileEntityDimDoor to use
RiftRegenerator instead for creating rifts when doors are broken.
3. Modified EventHookContainer to receive the chunk loaded event. We
iterate over the list of links in a loaded chunk and schedule them for
regeneration.
4. Reorganized the code in BlockRift. Divided the list of immune blocks
into two lists - one for DD blocks and one for regular MC blocks.
RiftRegenerator has to be able to distinguish between the two types.
5. Factored out some duplicate code from ItemRiftSignature and
ItemStabilizedRiftSignature. Most of the block immunity checks were used
to check if it would be safe to spawn a rift when using one of those
items. BlockRift.tryPlacingRift() covers all that logic in a single
function and makes the item code a little simpler.
Implemented Regeneration for BlockRift

1. Made it so that rifts regenerate when rift blocks are replaced by
other blocks.
2. Changed the rift regeneration scheduling functions to streamline
their use in other classes. Common code that was needed to validate
links before calling those functions has been moved into them so that
the checks are always performed internally.
Improved Door Code

1. Removed code from BaseDimDoor that was already implemented almost
identically in BlockDoor. Clarified some uses of setBlock() by changing
them to setBlockToAir() instead.
2. Removed TileEntityDimDoor.invalidate() and moved the regeneration
scheduling code to BaseDimDoor.breakBlock(). I would prefer to move away
from overriding the invalidate() method. This also simplifies the code
since we don't need to perform some of the checks we had in
breakBlock().
Improved Regeneration Code

1. Added code so that Transdimensional Trapdoors detect that they have
been broken and schedule rift regeneration at their location. This had
previously been neglected. Trapdoors deserve a little more attention.
2. Tweaked the breakBlock() code for BlockRift and BaseDimDoor so that
rift regeneration is only scheduled if the underlying block was removed.
We don't want that to happen if the only change was for metadata.
Cleaned up Transdimensional Trapdoor Code

Removed unnecessary code for the Transdimensional Trapdoor. Most of it
was code dedicated to updating TileEntityTransTrapdoor.hasRift. That
flag was never used for anything.
Minor Changes

Removed a pointless check in yCoordHelper and corrected some comments in
RiftRegenerator. It turns out that ChunkProviderServer.chunkExists()
returns whether a chunk is loaded, not whether it has already been
created.