Add support for color attribute

I wanted to add support for the color attribute (http://fullcalendar.io/docs1/event_rendering/eventColor/) to easily set the color of a particular event rather than using fullcalendar_colors and the color module (which I couldn't make work for some reason). The attached one-line patch adds this support.

In my specific instance, I created a preprocessor function to add the color value to the #events render array from a color_field value:

/**
 * Implements hook_preprocess_fullcalendar(&$variables)
 */
function mymodule_preprocess_fullcalendar(&$variables) {
  foreach ($variables['element']['content']['events'] as $key => &$event) {
    foreach ($event['#event'] as $delta => &$item) {
      if (!empty($event['#entity']->field_event_category)) {
        $term = taxonomy_term_load($event['#entity']->field_event_category[LANGUAGE_NONE][0]['target_id']);
        if (!empty($term->field_color)) {
          $item['#options']['attributes']['data-color'] = $term->field_color[LANGUAGE_NONE][0]['rgb'];
        }
      }
    }
  }
}