Allied territory cmddeny; AsyncChatEvent performance improvement

Config option territoryAllyDenyCommands is added, similar to territoryNeutralDenyCommands.

FactionsListenerChat, which does all the player format processing, is changed to use dynamic event priorities instead of ten event handlers. To do this, a private EventExecutor class is created, with the implementation (pretty much) copied from CraftBukkit.

Additionally, PlayerCommandPreProcessEvent tries to short-circuit some checks, but actually analysing is needed to determine where the real performance losses are.