add IPluginLateInitialization interface

Pilz.Plugins/IPluginLateInitialization.cs

@@ -0,0 +1,13 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace Pilz.Plugins
+{
+    public interface IPluginLateInitialization
+    {
+        abstract void LateInit();
+    }
+}