Added addPlugin() with TextTemplatePlugin

src/TextTemplate.php

@@ -105,6 +105,11 @@ public function addFunction ($functionName, callable $callback) {
         return $this;
     }
 
+    public function addPlugin (TextTemplatePlugin $plugin)
+    {
+        $plugin->registerPlugin($this);
+    }
+
     /**
      * Register all public Functions from an Object
      *

src/TextTemplatePlugin.php

@@ -0,0 +1,15 @@
+<?php
+/**
+ * Created by PhpStorm.
+ * User: matthes
+ * Date: 28.03.18
+ * Time: 15:05
+ */
+
+namespace Leuffen\TextTemplate;
+
+
+interface TextTemplatePlugin
+{
+    public function registerPlugin (TextTemplate $textTemplate);
+}