New events and functions, some changes

Add block_dispense, entity_change_block and vehicle_move events, extend player_portal_travel and entity_damage_player events, add entity_exists, sk_region_owners and sk_region_members functions, extend sk_region_info function.

I tried to add entity_move event, instead of vehicle_move as jb-aero proposed on IRC. Problem is that in bukkit is no event like entityMoveEvent or something similar.