Sorting for all listings & bugfixes for all listings except Newsletters

- newsletters listing now uses hash history
- newsletters are sorted by Subject (a->z)
- segments are sorted by Name (a->z)
- re-added WordPress Users list as a segment you can send a newsletter to
- added explicit error messages when an auto newsletter isn't fully configured
- added missing strings for "selectAll" in Segments listing
- fixed filters() in Subscribers listing (wrong count as it was not taking groups/filters/search into account)

lib/Config/Menu.php

@@ -399,7 +399,7 @@ class Menu {
     $data = array();
 
     $data['items_per_page'] = $this->getLimitPerPage('newsletters');
-    $data['segments'] = Segment::getSegmentsWithSubscriberCount();
+    $data['segments'] = Segment::getPublished()->findArray();
     $data['settings'] = Setting::getAll();
     $data['roles'] = $wp_roles->get_names();
     $data['roles']['mailpoet_all'] = __('In any WordPress role');