* [Mail/Parser/Relay] Fixed an issue with the '#comment' action on relay replies.
* [Calendars] Fixed a notice in calendars when using PHP 5.4+.
* [Virtual Attendants] All Virtual Attendant behaviors can now utilize a new '(Set a custom placeholder)' action to create synthetic placeholders using snippets and scripts.  This is similar to using private behavior variables, but custom placeholders don't need to be formally defined before they are used.
6.4.3-release checkpoint