Added title preprocessing

Fixes #3380

@aaronschachter 
This is kind of confusing. Could it go like this?

````
$vars['title'] = $vars['name'];
 if (empty($vars['field_title'])) {
  $vars['title'] = $vars['field_title'][0]['value'];
 }
````
Should then also add:
````
drupal_set_title($vars['title']);
`````
which sets the title in the `<HEAD>`

Also, you'll need to change the `taxonomy-term.tpl.php` to output `$title`.