Remove builtins imports

This module is not intended to be used directly in most cases, per:
https://docs.python.org/3/library/builtins.html

None of our usages warrant the explicit import. We also avoid some
confusion as folks dig to see what we are doing to require
importing builtins directly.

evennia/commands/cmdsethandler.py

@@ -63,7 +63,6 @@ can then implement separate sets for different situations. For
 example, you can have a 'On a boat' set, onto which you then tack on
 the 'Fishing' set. Fishing from a boat? No problem!
 """
-from builtins import object
 import sys
 from traceback import format_exc
 from importlib import import_module