Replace Agent.GetStepCount with Agent.StepCount` (#3476)

Project/Assets/ML-Agents/Examples/Hallway/Scripts/HallwayAgent.cs

     {
         if (useVectorObs)
         {
-            sensor.AddObservation(GetStepCount() / (float)maxStep);
+            sensor.AddObservation(StepCount / (float)maxStep);
         }
     }
 

com.unity.ml-agents/CHANGELOG.md

  - The stepping logic for the Agent and the Academy has been simplified (#3448)
  - Update Barracuda to 0.6.0-preview
  - The checkpoint file suffix was changed from `.cptk` to `.ckpt` (#3470)
+ - The method `GetStepCount()` on the Agent class has been replaced with the property getter `StepCount`
 
 ### Bugfixes
 - Fixed an issue which caused self-play training sessions to consume a lot of memory. (#3451)

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

             m_Brain = m_PolicyFactory.GeneratePolicy(Heuristic);
         }
 
-        /// <summary>
-        /// Current episode number.
+        /// Current step count.
-        public int GetStepCount()
+        public int StepCount
-            return m_StepCount;
+            get { return m_StepCount; }
         }
 
         /// <summary>

com.unity.ml-agents/Tests/Editor/MLAgentsEditModeTest.cs

 
                 Assert.AreEqual(i, aca.TotalStepCount);
 
-                Assert.AreEqual(agent2StepSinceReset, agent2.GetStepCount());
+                Assert.AreEqual(agent2StepSinceReset, agent2.StepCount);
                 Assert.AreEqual(numberAgent1Reset, agent1.agentResetCalls);
                 Assert.AreEqual(numberAgent2Reset, agent2.agentResetCalls);
 
                 expectedAgentStepCount += 1;
 
                 // If the next step will put the agent at maxSteps, we expect it to reset
-                if (agent1.GetStepCount() == maxStep - 1 || (i == 0))
+                if (agent1.StepCount == maxStep - 1 || (i == 0))
-                if (agent1.GetStepCount() == maxStep - 1)
+                if (agent1.StepCount == maxStep - 1)
                 {
                     expectedAgentActionSinceReset = 0;
                     expectedCollectObsCallsSinceReset = 0;
 
-                Assert.AreEqual(expectedAgentStepCount, agent1.GetStepCount());
+                Assert.AreEqual(expectedAgentStepCount, agent1.StepCount);
                 Assert.AreEqual(expectedResets, agent1.agentResetCalls);
                 Assert.AreEqual(expectedAgentAction, agent1.agentActionCalls);
                 Assert.AreEqual(expectedAgentActionSinceReset, agent1.agentActionCallsSinceLastReset);

docs/Migrating.md

 * The `Monitor` class has been moved to the Examples Project. (It was prone to errors during testing)
 * The `MLAgents.Sensor` namespace has been removed. All sensors now belong to the `MLAgents` namespace.
 * The `SetActionMask` method must now be called on the optional `ActionMasker` argument of the `CollectObservations` method. (We now consider an action mask as a type of observation)
+* The method `GetStepCount()` on the Agent class has been replaced with the property getter `StepCount`
+* Replace all calls to `Agent.GetStepCount()` with `Agent.StepCount`
 
 ## Migrating from 0.13 to 0.14