New ResourceLoader interfaces
New ResourceManager
Made LocaleManager compatible with new ResourceManager

Now its up to the Plugin Devs which file should be loaded with which Loader into which Locale. The Plugin Dev can register its own ResourceLoader implementations to load from even more Formats.

The loading of Language Files is now: getLocaleManager().load(Locale.US, "lang/en_US.yaml");. This example would be loaded with the builtin YML Resource Loader.