Add plug-in support

VAR.Toolbox.TestPlugin/FrmTestPlugin.cs

@@ -0,0 +1,17 @@
+using System.Windows.Forms;
+using VAR.Toolbox.UI;
+
+namespace VAR.Toolbox.TestPlugin
+{
+    public partial class FrmTestPlugin : Form, IToolForm
+    {
+        public FrmTestPlugin()
+        {
+            InitializeComponent();
+        }
+
+        public string ToolName { get { return "Test"; } }
+
+        public bool HasIcon { get { return false; } }
+    }
+}