Check that queues exist in nodequeue_extras_contextual_links_view_alter to preven notices

Hi, thanks for this module.
In the .module file on line 21 I think we need a check that queues are returned by nodequeue_get_qid_map(), or that the queue in question is in the returned array. It's probably a rare case, but if a queue is deleted and views still has the relationship in place, there are php notices.

$qid_map = nodequeue_get_qid_map();