Update client on cancelled leash. Fixes BUKKIT-4395
Update client on cancelled entity naming. Fixes BUKKIT-4396
Added EntityHorse for diff visibility.
Fix donkey/mule dupe exploit.
Minecraft spec has changed and we're required to follow. We now build with Java 6.
Fix scaling for player health. Fixes BUKKIT-4431
Properly clear attributes on remove and death. Fixes BUKKIT-4416
Improve maps.yml. Fixes BUKKIT-4419

Additionally fixed Minecart's interface to map INVALID methods.
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.