Manage subscriptions

- make use of the SubscriberSegment::status column to keep track of unsubscriptions
- unsubscribed segments now appear grayed out in the Subscribers listing
- added unsubscribed_at after segment names when editing a subscriber
- added date() method for Twig (uses WP's date format / date_offset)
- fixed typo in Form iframe export
- fixed unit test for Newsletters
- updated selection component (JSX) to allow more customization

lib/Models/Newsletter.php

@@ -52,6 +52,11 @@ class Newsletter extends Model {
     );
   }
 
+  function withSegments() {
+    $this->segments = $this->segments()->findArray();
+    return $this;
+  }
+
   function options() {
     return $this->has_many_through(
       __NAMESPACE__.'\NewsletterOptionField',
@@ -67,6 +72,12 @@ class Newsletter extends Model {
       ->findOne();
   }
 
+  function withSendingQueue() {
+    $this->queue = $this->getQueue();
+    return $this;
+  }
+
+
   static function search($orm, $search = '') {
     return $orm->where_like('subject', '%' . $search . '%');
   }