Fix decoding message/rtf822 part body/size

When e.g. an encrypted message has one of it's sub-parts a part that is message/rfc822
part we need it's body and size, because it will be listed on the attachments list
and also can be downloaded.

program/lib/Roundcube/rcube_mime_decode.php

@@ -192,6 +192,11 @@ class rcube_mime_decode
                 $obj = new rcube_mime_decode($this->params);
                 $return->parts[] = $obj->decode($body, false);
                 unset($obj);
+
+                if ($this->params['include_bodies']) {
+                    $return->body = $this->params['decode_bodies'] ? rcube_mime::decode($body, $encoding) : $body;
+                }
+
                 break;
 
             default: