Abstract Inventories & Inventory Components.

refactor how inventories are constructed to provide an API.
Adds inventory components to Zombie, Pig Zombie, Skeleton.
now have a 'Quickbar' for their held item slot, and ArmorInventory for armor.
CreatureProtocol now checks to see if an entity has Inventory and attempts to send worn/held item to clients.

Signed-off-by: Nick Minkler <sleaker@gmail.com>
Merge pull request #540 from Sleaker/master

Inventory API & EntityInventories
CommandBlock implementation

Signed-off-by: Walker Crouse <walkercrouse@hotmail.com>
Cleanup.
Signed-off-by: Chris Sanders <zidane@outlook.com>
Added basic pressureplate and tripwire collision shapes, fixes Vanilla-356

Signed-off-by: Irmo van den Berge <bergerkiller@gmail.com>
Increased complexity of ChunkDataMessage test and tweaked codec
Optimised array allocation when creating chunk packets
- initial compressed buffer size set to 25% of uncompressed size
- initial buffer expands as needed