Add RegionSizeX,RegionSizeY to Simulator class.

Add logic to copy region size info (if supplied) into Simulator class on instance creation.
Add region size fields to definitions of LoginResponse, EnableSimulator, TeleportFinishMessage, CrossedRegionMessage.
Add constants Simulator.DefaultRegionSizeX=256 and Simulator.DefaultRegionSizeY=256
Add display of region size in "RegionInfo" TestClient command

Programs/examples/TestClient/Commands/Stats/RegionInfoCommand.cs

@@ -19,9 +19,13 @@ namespace OpenMetaverse.TestClient
             output.AppendLine(Client.Network.CurrentSim.ToString());
             output.Append("UUID: ");
             output.AppendLine(Client.Network.CurrentSim.ID.ToString());
+
             uint x, y;
             Utils.LongToUInts(Client.Network.CurrentSim.Handle, out x, out y);
             output.AppendLine($"Handle: {Client.Network.CurrentSim.Handle} (X: {x} Y: {y})");
+
+            output.AppendLine($"Size: X: {Client.Network.CurrentSim.SizeX}, Y: {Client.Network.CurrentSim.SizeY}");
+
             output.Append("Access: ");
             output.AppendLine(Client.Network.CurrentSim.Access.ToString());
             output.Append("Flags: ");