ADD: return the root of the tree

include/Tree/tree.hpp

@@ -52,6 +52,22 @@ namespace Tree
     std::list<std::shared_ptr<Tree::BaseNode>> children;
 
   public:
+
+    /**
+    * @brief get the root of the tree
+    *
+    */
+    std::shared_ptr<Tree::BaseNode> getRoot()
+    {
+      if (parent==nullptr)
+      {
+        return shared_from_this();
+      }
+
+      return parent->getRoot();
+
+    }
+
     /**
     * @brief print the tree starting with the current node to stdout
     *