Cleanup: remove uneccesary cast
Minor: remove unneeded code from PlayerJoin/Respawn listeners.

* I assume event.getPlayer() will never be null as it's the player joining/respawning that triggered the event.
* Removed accidentally left in Gamemode.Creative check.
Minor: change POWERUP, PLAYERJOIN etc to POWER_UP, PLAYER_JOIN internally (powerup & playerjoin still supported in config)
Fix: issue with tool: <item>/<quantity> not being parsed.
Add: change HIT trigger to LEFTCLICK if it's on a block.

* this way users can use either hit or leftclick but both are correctly represented interally depending on a block or mob.
Release: version 2.8b.334