Added RepoRegistry and fixed GiveEvent injection
RepoRegistry allows for mods to have just a class to hold their block/item instances, and then register the class with the RepoRegistry, which handles the registrations with the GameRegistry. The test package has an example of that. It will be removed at some point. Also fixed GiveEvent injection. (I miscounted the INVOKEVIRTUAL opcodes between the end and where I wanted to inject)