Upgrading Checklist 0.11

Checklist

Flyweight and Identity

Artemis now passes most entities as either flyweights or int entity ids.

Avoid expensive int/Integer unboxing like so:

Before	After
Map<Entity,Object>	LibGDX's IntMap<Object>. For reasonable entity counts: Bag<Object>.
Bag<Entity>	IntBag

see https://github.com/junkdog/artemis-odb/blob/master/CHANGELOG.md for all breaking changes.