code: function ConfigFile(project_dir, platform, file_tag) {
      this.project_dir = project_dir;
      this.platform = platform;
      this.file_tag = file_tag;
      this.is_changed = false;
  
      this.load();
  }
docs: ****************************************************************************
  ConfigFile class
  
  Can load and keep various types of config files. Provides some functionality
  specific to some file types such as grafting XML children. In most cases it
  should be instantiated by ConfigKeeper.
  
  For plugin.xml files use as:
  plugin_config = self.config_keeper.get(plugin_dir, '', 'plugin.xml');
  
  TODO: Consider moving it out to a separate file and maybe partially with
  overrides in platform handlers.
  ****************************************************************************