Sensor API cleanup (#3480)

com.unity.ml-agents/Runtime/InferenceBrain/TensorProxy.cs

     /// allowing the user to specify everything but the data in a graphical way.
     /// </summary>
     [Serializable]
-    public class TensorProxy
+    internal class TensorProxy
     {
         public enum TensorType
         {

com.unity.ml-agents/Runtime/Sensor/ISensor.cs

         /// Note that this (and GetCompressedObservation) may be called multiple times per agent step, so should not
         /// mutate any internal state.
         /// </summary>
-        /// <param name="adapater"></param>
+        /// <param name="adapter"></param>
-        int Write(WriteAdapter adapater);
+        int Write(WriteAdapter adapter);
 
         /// <summary>
         /// Return a compressed representation of the observation. For small observations, this should generally not be

com.unity.ml-agents/Runtime/Sensor/WriteAdapter.cs

 
         TensorShape m_TensorShape;
 
+        internal WriteAdapter() { }
+
         /// <summary>
         /// Set the adapter to write to an IList at the given channelOffset.
         /// </summary>
-        public void SetTarget(IList<float> data, int[] shape, int offset)
+        internal void SetTarget(IList<float> data, int[] shape, int offset)
         {
             m_Data = data;
             m_Offset = offset;
         /// <param name="tensorProxy">Tensor proxy that will be writtent to.</param>
         /// <param name="batchIndex">Batch index in the tensor proxy (i.e. the index of the Agent)</param>
         /// <param name="channelOffset">Offset from the start of the channel to write to.</param>
-        public void SetTarget(TensorProxy tensorProxy, int batchIndex, int channelOffset)
+        internal void SetTarget(TensorProxy tensorProxy, int batchIndex, int channelOffset)
         {
             m_Proxy = tensorProxy;
             m_Batch = batchIndex;