[wip] Example project for the new API

Let's add an example project to the Injector pod, to show what you can do with it. Features to demonstrate:

+ [ ] Map class to subclass
+ [ ] Map class to object
+ [ ] Map class to block
+ [ ] Map protocol to class
+ [ ] Map protocol to object
+ [ ] Map protocol to block
+ [ ] Keeping references (pseudo singletons)
+ [ ] Remove after use
+ [ ] Lazy injection for all of the above