Implement command "land show". This shows all the parcels on the currently selected region/s

This is useful for diagnostics.  The command is "land show" rather than "show land" because it's implemented as a module specific subcommand.

OpenSim/Region/Framework/Interfaces/ILandObject.cs

@@ -43,7 +43,11 @@ namespace OpenSim.Region.Framework.Interfaces
         LandData LandData { get; set; }
         bool[,] LandBitmap { get; set; }
         UUID RegionUUID { get; }
+        Vector3 StartPoint { get; }
+        Vector3 EndPoint { get; }
+        
         bool ContainsPoint(int x, int y);
+        
         ILandObject Copy();
 
         void SendLandUpdateToAvatarsOverMe();