code: function(stringKey) {
              var self    = this,
                  value   = null;
  
              if (!stringKey) {
                  value = self.config;
              } else {
                  value = h.getProperty(self.config, stringKey);
              }
  
              return self.callFilters('valueGetConfig', value, arguments);
          }
docs: Retrieves the the value of any property or sub-object within the current
  mixitup configuration, or the whole configuration object.
  
  @example
  
  .getConfig([stringKey])
  
  @example <caption>Example 1: retrieve the entire configuration object</caption>
  
  var config = mixer.getConfig(); // Config { ... }
  
  @example <caption>Example 2: retrieve a named sub-object of configuration object</caption>
  
  var animation = mixer.getConfig('animation'); // ConfigAnimation { ... }
  
  @example <caption>Example 3: retrieve a value of configuration object via a dot-notation string key</caption>
  
  var effects = mixer.getConfig('animation.effects'); // 'fade scale'
  
  @public
  @instance
  @since       2.0.0
  @param       {string}    [stringKey]    A "dot-notation" string key
  @return      {*}