Merge 0.15.1 to master (#3755)

* Bumping version on the release (#3615)

* Update examples project to 2018.4.18f1 (#3618)

From 2018.4.14f1.  An internal package dependency was updated as
a side effect.

* Remove dead components from the examples scenes (#3619) (#3624)

* Improve warnings and exception if using unsupported combo

* add meta file

* fix unit test

* enforce onnx conversion (expect tf2 CI to fail) (#3600)

* Update error message

* Updated the release branch docs (#3621)

* Updated the release branch docs

* Edited the README

* make sure top-level timer is closed before writing

* Remove space from Product Name for examples

In #2588 it was suggested that the space in the Product Name for
our example environments causes confusion when using a default build
because of the need to escape the space in the build filename.

This change removes the space from the Product Name in the project's
player settings.

* [bug-fix] Increase 3dbal...

com.unity.ml-agents/Runtime/Academy.cs

         /// Unity package version of com.unity.ml-agents.
         /// This must match the version string in package.json and is checked in a unit test.
         /// </summary>
-        internal const string k_PackageVersion = "0.15.0-preview";
+        internal const string k_PackageVersion = "0.15.1-preview";
 
         const int k_EditorTrainingPort = 5004;
 

com.unity.ml-agents/package.json

 {
-	"name": "com.unity.ml-agents",
-	"displayName":"ML Agents",
-	"version": "0.15.0-preview",
-	"unity": "2018.4",
-	"description": "Add interactivity to your game with Machine Learning Agents trained using Deep Reinforcement Learning.",
-	"dependencies": {
-		"com.unity.barracuda": "0.6.1-preview"
-	}
+  "name": "com.unity.ml-agents",
+  "displayName": "ML Agents",
+  "version": "0.15.1-preview",
+  "unity": "2018.4",
+  "description": "Add interactivity to your game with Machine Learning Agents trained using Deep Reinforcement Learning.",
+  "dependencies": {
+    "com.unity.barracuda": "0.6.1-preview"
+  }
 }

docs/Migrating.md

 * Replace `Academy.RegisterSideChannel` with `SideChannelUtils.RegisterSideChannel()`.
 * Replace `Academy.UnregisterSideChannel` with `SideChannelUtils.UnregisterSideChannel`.
 
+
 ## Migrating from 0.14 to 0.15
 
 ### Important changes

ml-agents/mlagents/trainers/agent_processor.py

             self._process_step(
                 terminal_step, global_id, terminal_steps.agent_id_to_index[local_id]
             )
-
         # Iterate over all the decision steps
         for ongoing_step in decision_steps.values():
             local_id = ongoing_step.agent_id

ml-agents/mlagents/trainers/env_manager.py

 AllStepResult = Dict[BehaviorName, Tuple[DecisionSteps, TerminalSteps]]
 AllGroupSpec = Dict[BehaviorName, BehaviorSpec]
 
-
 logger = get_logger(__name__)