Add facet text callback & altering hook

When we are exposing CCK fields as facets the value of the field is displayed in the facets block. For example, on a CCK Text field that uses a select widget with allowed values like:

0|Yellow
1|Red
2|Green
3|Orange

the values 0, 1, 2, 3 will be used as $facet_text instead displaying "Yellow", "Red", "Green", "Orange".

The attached patch let modules alter the CCK facet text by adding a callback the apachesolr_search_get_cck_text() and implementing a new hook:

/**
 * Implementation of hook_apachesolr_search_get_cck_text_alter()
 *
 * @param $facet_text
 *   The initial value is the $facet value. The hook implementation shoul alter this variable.
 *
 * @param $facet
 *   The facet value.
 *
 * @param $field
 *   An array containing the CCK field informations taken from _content_type_info().
 *
 * @param
 *   An array containing additional parameters.
 */
function hook_apachesolr_search_get_cck_text_alter(&$facet_text, $facet, $field, $options) {
  if ($field['type'] == 'text') {
    $allowed_values = text_allowed_values($field);
    if (isset($allowed_values[$facet])) {
      $facet_text = $allowed_values[$facet];
    }
  }
  elseif ($field['type'] == 'nodereference') {
    if ($title = db_result(db_query("SELECT title FROM {node} WHERE nid = %d", $facet))) {
      $facet_text = $title;
    }
  }
}