Use correct packet data for toggling flying. Fixes BUKKIT-4989
Use strict lookup for op permission refresh. Fixes BUKKIT-4698

Adding or removing operators was mistakenly using a loose player lookup
method, which would cause a permission refreshes on an online player whos
name starts with the name of the (offline) opped player.

Add/Remove op operations are exact name match only and the permission
refresh will behave the same way.
Added RecipeBookClone from nms for diff visibility
Fix written books crashing the server. Fixes BUKKIT-4945

CraftBukkit modifies the IRecipe interface, adding new methods, so all
classes that implement IRecipe need to be imported and modified to add the
new methods.

Extending ShapelessRecipes implements the added methods and allows
RecipeBookClone to work with the Recipes API in a way that is consistent
with similar recipes, even if the recipe information present in the API
isn't technically correct.
Fix BlockCanBuildEvent returning null. Fixes BUKKIT-4972

A Block object is now passed in place of the previous id value, so the
obfuscated name for all subsequent arguments was shifted.  As such,
BlockCanBuildEvent was using the incorrect values for both the material
and the location of the event.

This is corrected by swapping the values into the correct order and
providing an id based upon the Block passed into the method.
Maintain old setType method in WorldGenerator. Fixes BUKKIT-4915

WorldGenerator setType and setTypeAndData have their arguments changed to
add in support for CraftBlockChangeDelegate, which changes the method
signature. This change in the method signature breaks any WorldGenerators
that aren't modified to use CraftBlockChangeDelegate.

This commit fixes the issue by readding the old method and maintaining the
CraftBlockChangeDelegate method.  This makes it so that there is a
compatible method for both  CraftBlockChangeDelegate WorldGenerators and
unmodified WorldGenerators.

Additionally, this commit reduces and corrects the diffs in
WorldGenerator, moving the fix for layering violations to
CraftBlockChangeDelegate.
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
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