Correctly fire VehicleExitEvent. Fixes BUKKIT-3761

This change makes it so that EntityHuman#setPassengerOf(Entity) invokes
its parent method when leaving vehicles so that VehicleExitEvent is fired
for players leaving vehicles.

This change also fixes BUKKIT-2110, making it so VehicleExitEvent
correctly handles cancellation. The implementation of VehicleExitEvent
completely ignored the cancellation state of the event, making it so that
cancelling the event had no effect.  Cancelling a VehicleExitEvent now
causes the entity to remain inside of the vehicle, with no visual stutter.
Use ambient setting of potion effects. Fixes BUKKIT-4357 and BUKKIT-3653

This changes livingEntity.addPotionEffect(PotionEffect, boolean) to
construct the MobEffect using the constructor that includes the ambient
setting as supplied by the PotionEffect

This also changes livingEntity.getActivePotionEffects() to construct the
PotionEffects using the ambient setting supplied by the MobEffects.
POM Changes
mc-dev imports
Skeleton API Implementations
Spigot Configuration
Better Chunk Tick Selection
Crop Growth Rates
More Efficient Chunk Save Queue
More Efficient GetCubes
Proxy IP Filter
Merge tweaks and configuration

This allows the merging of Experience orbs, as well as the configuration of the merge radius of items. Additionally it refactors the merge algorithm to be a better experience for players.
LongHash Tweaks
Async Operation Catching

Catch and throw an exception when a potentially unsafe operation occurs on a thread other than the main server thread.
View Distance

This commit allows the user to select per world view distances, and view distances below 3. Be wary of the issues selecting a view distance of 1 or 2 may cause!
Compressed Nibble Arrays

Implement 'lightening' of NibbleArrays - only allocate
 buffers when non-trivial value Saving from 40-45% of memory use by chunk
 section data.

Finish up NibbleArray lightening work - use for Snapshots, reduce copies

Fix nibble handling with NBT - arrays aren't copied by NBTByteArray
Sync Free Chunk Reference Cache
Highly Optimized Tick Loop
Improved Timings System

Tracks nearly every point of minecraft internals and plugin events to give a good quick overview on what is causing TPS loss.
Orebfuscator