message: fix bug: add also subchilds when child will be added
diff: @@ -317,5 +317,9 @@ void DiffTreeModel::Node::addChild(const QStringList& pathPart, int indexFirstDi
  }
  }
  - mChildren.append(new Node(pathPart[indexFirstDifferent], this));
  + auto n = new Node(pathPart[indexFirstDifferent], this);
  + if (indexFirstDifferent + 1 < pathPart.length()) {
  + n->addChild(pathPart, indexFirstDifferent + 1);
  + }
  + mChildren.append(n);
  }
  