removed calls to reset from init (#2394)

* removed all calls to reset

* passing tests

* fix off-by-one error

* revert

* merge master into branch

* add OrderEnforcing Wrapper

* add orderenforcing to the docs

* add option for disabling

* add argument to EnvSpec

gym/wrappers/order_enforcing.py

@@ -0,0 +1,16 @@
+import gym
+
+
+class OrderEnforcing(gym.Wrapper):
+    def __init__(self, env):
+        super(OrderEnforcing, self).__init__(env)
+        self._has_reset = False
+
+    def step(self, action):
+        assert self._has_reset, "Cannot call env.step() before calling reset()"
+        observation, reward, done, info = self.env.step(action)
+        return observation, reward, done, info
+
+    def reset(self, **kwargs):
+        self._has_reset = True
+        return self.env.reset(**kwargs)