add a simple plugin system

Pilz.UI.Telerik.SymbolFactory/Extensions.cs

@@ -0,0 +1,25 @@
+using System;
+using System.Collections.Generic;
+using System.Drawing;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using Telerik.WinControls;
+using Telerik.WinControls.Svg;
+
+namespace Pilz.UI.Telerik
+{
+    public static class Extensions
+    {
+        public static Image ToImage(this RadSvgImage svg)
+        {
+            return svg?.Document.Draw(svg.Width, svg.Height);
+        }
+        
+        public static void ApplyColor(this RadSvgImage svg, Color color)
+        {
+            svg.Document.Fill = new SvgColourServer(color);
+            svg.ClearCache();
+        }
+    }
+}