Injecter

This is a dependency injector specifically designed for use with Yours Bitcoin. In order to allow injecting dependencies, Yours Bitcoin classes provide an "inject" method that makes a new class with injected dependencies. However, that method by itself presents a problem, because it creates a new class every time it is used, leaving the burden of caching the classes to the user. Thus the injector allows us to easily wrap an inject method that keeps a cache of the created classes, lowing memory burden, and allowing the instanceof operator to work correctly.