[stdlib-sig] Proposal: new "interpreter" module

I originally brought this in the discussion about removing types, but it can be separate. Through the years, sys has gather a fare share of crud. Much of these new additions are low-level and CPython specific. I believe the sys module should strive to be an interpreter neutral, clean module. Hence, I propose the "interpreter" module. We could move all those internal functions like _getframe(), get/setrecursionlimit(), get/setcheckinterval(), etc to it. Also, if we decided to remove the types module, this would be a natural place for frames and code objects. I look forward to your comments. -- Cheers, Benjamin Peterson