firehose fixes and optimisations. In particular get rid of the unresponsive script warning when trying to load updates (sine they aren't our posts, we can't check for unseen, hence we can't really load updates). Also make the url selection pluggable.

include/conversation.php

@@ -1384,10 +1384,10 @@ function network_tabs() {
 	// tabs
 	$tabs = array(
 		array(
-			'label' => t('Public'),
+			'label' => t('External'),
 			'url'=>$a->get_baseurl(true) . '/' . $cmd . '?f=&fh=1' . ((x($_GET,'cid')) ? '&cid=' . $_GET['cid'] : '') . ((x($_GET,'gid')) ? '&gid=' . $_GET['gid'] : ''), 
 			'sel'=> $public_active,
-			'title'=> t('View Public Streams'),
+			'title'=> t('Imported public streams'),
 		),
 
 		array(