Update to 1.10 and 1.11

• Fix almost all outstanding bugs on modern versions
• Switch metrics to bStats
• Major refactoring:
  • Make pet classes inherit from their respective NMS classes.
  • Refractor the majority of entity classes to be version independent, with small stub classes generated at runtime.
    • The version-dependent modules are now much smaller and have been
      cleaned up significantly, containing just the bare minimum we need beyond
      the bukkit API.
  • Switch to gradle
  • Download libraries at runtime instead of shading them. (no good reason)
  • Refractor entity spawning to allow chaning a pet's entity type
    • As of 1.11 each guardian, horse, zombie, and skeleton type has it's own
      unique entity type. Instead of being able to switch the type of the
      current entity, we have to respawn these entities when we want to switch
      types. The advantage of this approach is it allows us to keep
      compatibility with older versions that don't have seperate types.
  • Rewrite lots of things in kotlin
  • Version each development build based on git commit