Pass colgroups and sticky properties from theme_tree_table() to theme_table()

The theme_tree_table() function directly passes its $variables array to the theme_table() function. This is convenient because it means that you can set various properties from the parent caller.

For example theme_token_tree() uses this functionality:

  $element += array(
    '#theme' => 'tree_table',
    '#header' => array(
      t('Name'),
      t('Token'),
      t('Description'),
    ),
    '#rows' => $rows,
    '#attributes' => array('class' => array('token-tree')),
    '#empty' => t('No tokens available'),
    '#attached' => array(
      'js' => array(drupal_get_path('module', 'token') . '/token.js'),
      'css' => array(drupal_get_path('module', 'token') . '/token.css'),
      'library' => array(array('token', 'treeTable')),
    ),
  );

On my site I have overridden theme_token_tree() to customize its markup, and I would like to make the generated tree table not use the "sticky" table header. Just like the other properties, I should be able to simply set #tree = FALSE to set the sticky option. Unfortunately because the "sticky" option is not listed in hook_theme() in token.module, the #sticky property is never passed along to the theme function. The same problem also exists for the #colgroups option which is supported by theme_table(). This patch adds both missing properties to token_theme().