added get(LivingEntity) to retrieve previously assigned entities
added getOrAssign(LivingEntity) to retrieve or auto-assign entity
added new unassing-method
changes for AI behaviors:
created enum AIType - a list of ALL possible AI parts
more specific behavior removal options - using AIType you can filter even default behaviors
created enum AIState
created interface AIPart - representing exactly one part of the AI, determining whether it's default or custom, used for state monitoring and specific removal
AI behaviors are now re-usable
better checks for class-dependent behaviors (added generics)
auto-sorting of behaviors by given priorities
fixed a bug that caused not-updating of auto-generated priorities for AI behaviors
more methods to retrieve and check for certain AI types
added new attribute API
added Attribute interfaces: control a single entity attribute by changing basis value or adding modifiers
added AttributeModifier: based on a modify operation, changes attribute values at runtime
added movement speed, attack damage, knockback resistance and max health as attributes
