MapRenderer: Only cleanup if there's something to clean.
MapRenderer: Only cleanup if there's something to clean.

--- a/ARMapRenderer.cs
+++ b/ARMapRenderer.cs
@@ -252,13 +252,20 @@
 
 		public void Cleanup()
 		{
-			foreach (LineRenderer lineRenderer in this.vesselLineRenderers.Values)
-			{
-				lineRenderer.enabled = false;
-				GameObject.Destroy(lineRenderer.gameObject);
-			}
-			this.vesselLineRenderers.Clear();
-			this.vesselFrameCache.Clear();
+			if (this.vesselLineRenderers != null && this.vesselLineRenderers.Count > 0)
+			{
+				foreach (LineRenderer lineRenderer in this.vesselLineRenderers.Values)
+				{
+					lineRenderer.enabled = false;
+					GameObject.Destroy(lineRenderer.gameObject);
+				}
+				this.vesselLineRenderers.Clear();
+			}
+
+			if (this.vesselFrameCache != null && this.vesselFrameCache.Count > 0)
+			{
+				this.vesselFrameCache.Clear();
+			}
 		}
 	}
 }

--- a/AntennaRelay.cs
+++ b/AntennaRelay.cs
@@ -80,10 +80,9 @@
 		}
 
 		/// <summary>
-		/// Gets the first occluding body.
-		/// </summary>
-		/// <value>The first occluding body.</value>
-		public CelestialBody firstOccludingBody
+		/// Gets the first <see cref="CelestialBody"/> found to be blocking line of sight.
+		/// </summary>
+		public virtual CelestialBody firstOccludingBody
 		{
 			get;
 			protected set;

--- a/ProtoAntennaRelay.cs
+++ b/ProtoAntennaRelay.cs
@@ -70,16 +70,6 @@
 			}
 		}
 
-
-		public CelestialBody firstOccludingBody
-		{
-			get
-			{
-				return base.firstOccludingBody;
-			}
-		}
-
-
 		/// <summary>
 		/// Gets a value indicating whether this <see cref="AntennaRange.ProtoDataTransmitter"/> has been checked during
 		/// the current relay attempt.