Switch tortoise movement to NavMeshAgent

Remove turtle animation of patrolling a route
and switch to using NavMeshAgent to patrol between
points.

Assets/Patrol.cs

@@ -0,0 +1,48 @@
+// Patrol.cs
+using UnityEngine;
+using UnityEngine.AI;
+
+public class Patrol : MonoBehaviour 
+{
+    public Transform[] points;
+    private int destPoint = 0;
+    private NavMeshAgent agent;
+
+    void Start () 
+    {
+        agent = GetComponent<NavMeshAgent>();
+
+        // Disabling auto-braking allows for continuous movement
+        // between points (ie, the agent doesn't slow down as it
+        // approaches a destination point).
+        agent.autoBraking = false;
+
+        GotoNextPoint();
+    }
+
+
+    void GotoNextPoint() 
+    {
+        // Returns if no points have been set up
+        if (points.Length == 0)
+        {
+            return;
+        }
+
+        // Set the agent to go to the currently selected destination.
+        agent.destination = points[destPoint].position;
+
+        // Choose the next point in the array as the destination,
+        // cycling to the start if necessary.
+        destPoint = (destPoint + 1) % points.Length;
+    }
+
+
+    void Update () 
+    {
+        // Choose the next destination point when the agent gets
+        // close to the current one.
+        if (!agent.pathPending && agent.remainingDistance < 0.5f)
+            GotoNextPoint();
+    }
+}