Use bias in the CLI and make model objects immutable (#66)

* Use bias in the CLI

* Make model objects immutable and improve dotdict

Author: schneiderfelipe

overreact/io.py

@@ -4,6 +4,7 @@
 
 from collections.abc import MutableMapping
 from collections import defaultdict
+from copy import deepcopy as _deepcopy
 import json
 import logging
 import os

overreact/misc.py

@@ -13,6 +13,7 @@
 
 import overreact as rx
 from overreact import constants
+from overreact import core as _core
 
 
 def _find_package(package):