Many things to express. This change implements the EntityTeleportEvent in a context thread safe way. The following are handled:
- Passengers have the event called properly
- Recursion is prevented by checking for the teleport status. Such status is revoked by overriding and chaining the teleport callback. It is manually removed when the event fails and henceforth the callback would call null, or when the entities are in the same chunk region, and hence don't call the callback.
- Teleporting status is removed on callback
- Modifying the teleport location of passenger entities is forbidden to prevent conflicts
- Cancelling an entity riding will dismount it and NOT trigger any events for its passengers

… bukkit event api

- Reworked listeners. Now they execute synchronously after any edits including chunk loading. This allows for perfect asynchronous linear behaviour (tested!)
- Reworked bukkit event api, introduced callEventAsync. If old method is call, the event is at risk of not having the proper data if paired up with any kind of chunk loading or non-direct modifier which is called asynchronously. This is the best we could possibly do without creating conflicting behaviour
- Fixed teleportation whoopsie I made

…usly fetched thread context

- If the current thread is not a region --> run consecutive code on current thread
- If the origin of the event is unspecified --> heuristical approach at fetching current thread coords by taking a random coordinate in current map of thread. This can go wrong so easily, SpottedLeaf, this one's on you, I trust that you'll help me improve this
- If the origin of the event is specified -> return to thread context at specified location (hurray)

Additional improvements:
- Made nms command /teleport depend on bukkit handling to support proper event handling
- Added player teleportation to the handlers. All player teleports now have the same behaviour as chunk fetches (yipee)
- Fixed a scenario of chunk loading I forgot about

Implemented the following events:
-  PlayerSpawnLocationEvent,
-  EntityPortalEnterEvent,
-  EntityPortalExitEvent,
-  PlayerPortalEvent,
-  EntityPortalReadyEvent

…hread and offthread events

- Fixed issue where global thread events wouldn't be properly accounted for
- Fixed an issue where the EntityEnterPortalEvent would be fired every tick (god knows how long this has been there like this)

…rigin location

- Fix non-region threads calling teleport and chunk functions failing 
- Fixed wrong origin level in player and entity portal event