Makes Address and Processor internal. Renames the EF-specific extension to DecompileAsync

RE #35. I renamed the extension to DecompileAsync to match the subsequent XYZAsync calls that are the whole point for having an alternate extension.

I also went ahead and made Address and Processor internal to avoid name clashes since those are pretty common names and there's really no need for them to be public.

Obviously feel free to go a different direction or reject the changes, just figured I would take a shot at it since these were pretty minor.