Fixes BUKKIT-589: if you call damage on an instance of EnderDragon, no damage
is done.
Reason for bug: damage calls Entity.damageEntity. But EntityComplex
overrides damageEntity to do nothing.
Fix: CraftComplexLiving should call EntityComplex.e instead of
Entity.damageEntity. e is the method that actually does damage to an
instance of EntityComplex.
Also, standardise getHandle and clean up in general.
getHandle is now using the 'entity' member variable instead of
super.getHandle, as this reduces the number of chained calls needed.
