Support for cloning ChanServ levels between channels

I needed a way to clone levels between two channels, so I modified cs_clone and a core header (and associated source) file to add this functionality.

Modification compiles and runs smoothly on my network.

Sorry for the bad commit name in the diff. I tried to edit it, but it didn't take apparently.
You could also just loop over the defined levels in the config, but if you want to do this I would probably just make the method return a const reference the underlying map.