Reduce code duplication between core forum and advanced forum

AF takes over a ton of stuff from core forum. Since this has happened organically, I don't even know what's left un-overridden anymore. Need to take some time and analyze what is still being used from core forum and see if it would make more sense to take that over as well and ditch core. If not that, at least need to disable some of the template_preprocess functions that are being 95% overwritten anyway.

Michelle