ObjectFactory builds an instance, given a class constant
TypeResolver is the first of many possible identifier resolvers

It assumes the identifier is a class name, and builds an instance of that class.
Retrieve an instance using an alias
Spec cleanup
The same instance of a service is returned within a single request
Isolate aliases in config

Will allow other kinds of configuration.
Retrieve a configured value object
All instances from an injector are singletons
Merge values support