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
Spigot
EMC POM changes
Misc EMC Changes

Only spawn 1 ocelot ever from eggs.
Load custom permissions before plugins
Unload plugins after everything else
Color name tags to match list
Make Durability enchant scale 0-80% reduction on Armor damage (up to level 5)
Zombies break down doors on normal
Update inventory on block place/interact cancellation
Get rid of yellow disconnect log
Anti Dupe

Remove CraftBukkit "Feature" of ItemStack's having infinite use if less than 0 stack size.
Blocks most cases of < 0 itemstack dupe bugs
Mob Spawning Events

Add 2 events for better control of mob spawning (Natural and Spawners) This allows us a much more powerful control over spawning and improve performance
PlayerUseItem Event

This lets us control when an item is consumed and change the item.
EMC Anvil Tweaks

Make Items not have a repair cost increase due to Anvil usage.
Renaming is only 5 levels, combines include free renames.
Hidden Item Meta

This adds the ability to store hidden metadata in item lore.

Simply set a line to "&&::META" and every blank line before, that line, and every line after will be hidden from view on the client.

for example, you can set &&::META on line 20, and there will not be 19 blank lines before it.
Then you can store Data on 21+

Also adds a &&::SHINY tag to send a fake enchantment aura if it does not exists.
Must be set before META
NIOM - NIO Manager

Alternative to Netty
improve the existing network manager using Blocking NIO instead of IO (more effecient code)
Writes use a direct memory buffer for less copying, and more stable memory usage.

Reimplement Low Priority Queue
Optimized PacketQueue System that supports instant send notification to the writer thread
Removed packet queue walking since it will very unlikely ever be hit now.
Writer thread will now sleep longer until notified
Network threads are no longer interrupted every tick, letting them sleep as much as possible
Persistent Meta API

This adds an API for getting and setting PERSISTENT Metadata
Meta data can be stored on Worlds, Entities, Chunks and at a Block level.
Meta is is provided in a simple Map/List setup and does not expose raw NBT access.
Chunk Save Reattempt

We commonly have "Stream Closed" errors on chunk saving, so this code should re-try to save the chunk in the event of failure and hopefully prevent rollbacks.
Keep certain items on death API

This adds a getItemsToKeep to PlayerDeathEvent that can be modified for what item a player should keep upon death.

This can be used for never-to-be-dropped items.
Anvil Event

Fire an event for anvil usage
ArrowHitBlock Event
Entity Spawn Events

These events fire any time an entity is added/removed to the world, so we do not
have to check multiple locations for entities being added/removed from the world.
Precise timings
Show 1/10s TPS averages