Add Client to Player

A reference to the player's client is added to the Player class in order
to account for future requests where the client may be needed to bridge
between the server layer and the game layer.
Extract out hitpoint behavior to Actor
Add turnToFace method to Actor class

This method will be used for turning to a specified Entity in the game
world
Implement getMaxHitpoints in Npc class
Make Appearance constructor default (package-private)

The preferred style of creating an Appearance object will be with the
AppearanceBuilder class
Reformat setAppearance documentation
Add Consumable and Consumer classes

The Consumable class will be used for different types of consumable
items (food, potions, etc). This may also end up being used with potion
mixing.

The Consumer class will be used for actors that have the ability to
consume (which will be all of them).