Merging master into release_10_tmp before merge release_10_tmp into master

com.unity.ml-agents/CHANGELOG.md

 [Semantic Versioning](http://semver.org/spec/v2.0.0.html).
 
 
+## [Unreleased]
+### Major Changes
+#### com.unity.ml-agents (C#)
+#### ml-agents / ml-agents-envs / gym-unity (Python)
+
+### Minor Changes
+#### com.unity.ml-agents / com.unity.ml-agents.extensions (C#)
+#### ml-agents / ml-agents-envs / gym-unity (Python)
+
+### Bug Fixes
+#### com.unity.ml-agents (C#)
+#### ml-agents / ml-agents-envs / gym-unity (Python)
+
+
 ## [1.6.0-preview] - 2020-11-18
 ### Major Changes
 #### com.unity.ml-agents (C#)

com.unity.ml-agents/CONTRIBUTING.md

 
 ## Environments
 
-We are also actively open to adding community contributed environments as
-examples, as long as they are small, simple, demonstrate a unique feature of the
-platform, and provide a unique non-trivial challenge to modern machine learning
-algorithms. Feel free to submit these environments with a PR explaining the
-nature of the environment and task.
+We are currently not accepting environment contributions directly into ML-Agents.
+However, we believe community created enviornments have a lot of value to the
+community. If you have an interesting enviornment and are willing to share,
+feel free to showcase it and share any relevant files in the
+[ML-Agents forum](https://forum.unity.com/forums/ml-agents.453/).
 
 ## Continuous Integration (CI)
 

gym-unity/gym_unity/__init__.py

 # Version of the library that will be used to upload to pypi
-__version__ = "0.22.0"
+__version__ = "0.23.0.dev0"
-__release_tag__ = "release_10"
+__release_tag__ = None

gym-unity/gym_unity/tests/test_gym.py

     assert isinstance(done, (bool, np.bool_))
     assert isinstance(info, dict)
 
-    # check behaviour for allow_multiple_obs = False
+    # check behavior for allow_multiple_obs = False
     env = UnityToGymWrapper(mock_env, uint8_visual=use_uint8, allow_multiple_obs=False)
     assert isinstance(env, UnityToGymWrapper)
     assert isinstance(env.observation_space, spaces.Box)
     assert isinstance(done, (bool, np.bool_))
     assert isinstance(info, dict)
 
-    # check behaviour for allow_multiple_obs = False
+    # check behavior for allow_multiple_obs = False
     env = UnityToGymWrapper(mock_env, uint8_visual=use_uint8, allow_multiple_obs=False)
     assert isinstance(env, UnityToGymWrapper)
     assert isinstance(env.observation_space, spaces.Box)

ml-agents-envs/mlagents_envs/__init__.py

 # Version of the library that will be used to upload to pypi
-__version__ = "0.22.0"
+__version__ = "0.23.0.dev0"
-__release_tag__ = "release_10"
+__release_tag__ = None

ml-agents/mlagents/trainers/__init__.py

 # Version of the library that will be used to upload to pypi
-__version__ = "0.22.0"
+__version__ = "0.23.0.dev0"
-__release_tag__ = "release_10"
+__release_tag__ = None