subscriptions 6.x-1.4

This is version 1.4 of Subscriptions for Drupal 6.

Changes since 1.3:
Enhancements:
- #1007566, #952170: Add ID mailvars: !recipient_uid, !nid, !sender_uid, !comment_uid, !comment_cid, !comment_nid.
- #928116: Add subscriptions_mail_trash_silently kill-switch.
- Default to suppress notifications on bulk node updates.
- #840812: Clarify "digest mode" description in the case where the "send interval" is inaccessible.
- Implement suspending sending of notifications and avoid using obsolete mail addresses.
Bugs fixed:
- Fix links in suspension message.