Scale line-width to match zoom.

OpenRA.Renderer.Null/NullGraphicsDevice.cs

@@ -48,6 +48,7 @@ namespace OpenRA.Renderer.Null
 		}
 
 		public void DrawPrimitives(PrimitiveType pt, int firstVertex, int numVertices) { }
+		public void SetLineWidth( float width ) { }
 
 		public IVertexBuffer<Vertex> CreateVertexBuffer(int size) { return new NullVertexBuffer<Vertex>(); }
 		public ITexture CreateTexture() { return new NullTexture(); }