add newline feature to the text node, add about window with credits, add about menu with submenus

src/node_text.cpp

@@ -54,7 +54,7 @@ void NodeText::parse_attributes(kAttribute ka, const tinyxml2::XMLAttribute* att
     switch (ka)
     {
     case kAttribute::Text:
-        m_text = attr->Value();
+        m_text = unescape(attr->Value());
         break;
     case kAttribute::FontFace:
         m_font = attr->Value();