Enhancements

Adds the new method, .components_of_types( uuid, *type ), to the
EntityManager (alias: .any( uuid, *type )).

This method returns a 2D array mapped against the given types, in order.
Each sub-array contains any components of the given type that are
attached to the entity.

This commit also changes several uses of EC functions to instead use the
shorthand aliases, making the source code easier to read.