Add API to control scaled health. Adds BUKKIT-4590

This commit implements the ability to set the scale of hearts that the
client renders.  When the Packet44UpdateAttributes packet is sent, the
max health attribute is replaced with a scaled version, to preserve the
scaled health illusion clientside.

In order to accurately display the scaled health for players, a true
health is stored within CraftPlayer, and the datawatcher now stores the
scaled health. The getHealth() method for players still returns their
true health.

Changed setHealth() within EntityLiving to appropriately handle health
for instances of EntityPlayer. Inlined a call to
setHealth(getMaxHealth()) within the EntityLiving constructor to work
around CraftEntity instantiation.

Additionally fixes the health values sent when eating food within
FoodMetaData and ItemFood, which previously sent the unscaled health;
this commit alters them to send the properly scaled health.

Additionally fixes BUKKIT-4535, BUKKIT-4536, and BUKKIT-4127
Check interactable items before event. Fixes BUKKIT-4576

Items that cause entities to change state, including tags, chest, and
leashes, do not update the client properly following the firing of
PlayerInteractEntityEvent. This change makes the item checks occur
before the event fires, to concur with the client's assumptions.
Fix CraftBukkit diffs
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.