Implement tuple.__add__, dict.__contains__ and builtin id() function

The __contains__ method crashes the runtime when using the 'dict' type directly

eg.  
1 in dict()  # fails deep down in stl

Also for id() I took the cpython approach by casting the address of the Box* to i64.  I noticed thats an llvm type, is that correct?
 
How about let's XOR this with some constant -- while I don't know if it'd be a problem in practice, having the ids be the exact pointer value won't play well with the conservative GC which will think that the returned integers are actual pointers to the object.  XOR'ing them will make the int value not point into the heap and should let us avoid that.