Changelog:
- Fixed double teleport/repeated teleport with horizontal portals due to teleportation not being checked via the player's eye position.
- Fixed glitch where the player can get "stuck" between two sides of the portal when one is blocked off.
- Fixed concurrency bug with cross-server portals.
- Fixed cross-server teleportation failing causing player to be removed from the server, stopping portal effects from happening instead of just printing an error message.
- Fixed /bp reload on one server not properly clearing block arrays, causing a cross-server portal to stop working.
- Fixed one server disconnecting from the proxy then reconnecting causing an invalid block array to be sent, stopping you from seeing through a cross-server portal.
- Fixed server unregistering sometimes not working correctly.
- Fixed player velocity not being preserved when going through a cross-server portal.
- Fixed player flight status (elytra & just regular flight) not being preserved when going through a cross-server portal.
- Fixed player velocity not being preserved when going through a cross-server portal.
- Changed default teleportation cooldown to 2 ticks.
- Changed /bp origin and /bp destination to display the X, Y, Z, world and direction to the player in order to make getting the coordinates for cross-server portals easier.
- Enabled hiding of entities for cross-server portals. (not viewing entities through them, that's not going to happen for a long time)
- Fixed concurrency bug in ReflectUtils

Had to get this out ASAP to fix a bunch of bugs with cross-server portals.