Add VICE or Denise to Replace the C64 Core

[alyosha-tas]

I think if we are considering core replacements this one might have the highest utility. Our core is super slow and there isn't much to be done about it. Also audio emulation really requires the low level approach that VICE uses, not my hacky FFT approach that doesn't really work that well anyway. For a system that's known for it's audio I think that is pretty important. Also VICE has higher overall accuracy and compatibility.

VICE homepage

Another option is Denise, which VICE's testrom tracker claims to be the most accurate. (Denise since 2.0 also supports some Amiga systems we don't emulate.)

[nattthebear]

Thanks for adding this. It'll probably be some time before I start new core porting, but I want to get the ducks in a row, so to speak. Lots of knowledge on potential core ports is locked up in rando TASVideos threads.