Controls, projectiles, items

Modifications have been made to how controls work for a more consistent
interface.

Projectiles have become the base class for every Item, and Items are the
base class for anything that a Character can pick up. This should work
out nicely.

This new class structure is incomplete but the fundamentals are there.
Items have a use function that Characters can invoke. For example, a
ranged weapon's use function would shoot a bullet of some kind.

Different types of weapons will need their own classes to handle usage
and such things in different ways (WeaponMelee, WeaponGun, WeaponBow).
Can't yet decide whether Arrows (for bows) will extend Bullets or not.