Removed unnecessary using directives left over from migration

hexworld/Driver.cs

@@ -1,7 +1,4 @@
-using System;
-using Newtonsoft.Json;
-
-namespace hexworld
+namespace hexworld
 {
     public class Driver
     {

hexworld/HexRender.cs

@@ -1,5 +1,4 @@
 using System;
-using System.Drawing;
 using System.IO;
 using System.Linq;
 using Diamond;