World: load size directly from JSON.

Shared/World.cs

@@ -25,19 +25,16 @@ namespace SemiColinGames {
     public Camera Camera { get; }
 
     // Size of World in pixels.
-    public int Width {
-      get { return gridWidth * TileSize; }
-    }
-
-    public int Height {
-      get { return gridHeight * TileSize; }
-    }
+    public readonly int Width;
+    public readonly int Height;
 
     public World(GraphicsDevice graphics, string json) {
       Camera = new Camera();
       LinesOfSight = new LinesOfSight(graphics);
 
       JObject root = JObject.Parse(json);
+      Width = root.SelectToken("width").Value<int>();
+      Height = root.SelectToken("height").Value<int>();
 
       List<Tile> hazardTiles = new List<Tile>();
       List<Tile> obstacleTiles = new List<Tile>();