* [Mail/Filtering/Virtual Attendants] When a Virtual Attendant changes the 'Subject:', 'In-Reply-To:', or 'References:' headers in mail filtering behavior, Cerb will now check again to see if the message is a reply to an existing ticket.  Previously, the new/reply distinction was made before VAs ran and header changes didn't affect it.  This allows VAs to thread new mail based on anything (independent reference IDs, sender + subject, etc).
* [Mail/Filtering/Virtual Attendants] The 'Set header' action on Virtual Attendant mail filtering behaviors now internally handles the header name in lowercase.  It was previously possible for VA behaviors to create duplicate headers with different cases (e.g. 'Subject:' vs 'subject:').
[Code Cleanup]
* [CHD-3980] [Worklists/Quick Search/Workers] On worker worklists, it is now possible to quick search by group membership.
* [Worklists/Import/Usability] When importing records from a CSV file on worklists, the 'Match' column now provides a tooltip with more information about how it should be used.  Previously, some workers were clicking 'Match' for too many fields and preventing imports from working properly.  Fields are matched to determine uniqueness.
* [CHD-3980] [Worklists/Quick Search/Workers] When quick search filtering a worker worklist by the Groups field, it is now possible to use placeholders that contain a group id.  This is particularly useful in Virtual Attendants; for instance, to build a list of workers based on the roster of the current ticket's group.
* [Virtual Attendants/Simulator/Relay] Implemented simulator output for the 'Relay email' action in Virtual Attendants.
* [Virtual Attendants/Mail/Relay] When Virtual Attendants use the 'Relay mail' action, worker-based behavior variables can now be used to specify worker recipients.  Previously only owner, watchers, and explicitly selected workers could be specified.  Now it's possible to define a worker list behavior variable and use it as a relay list.  For instance, this is very useful for behaviors like 'Relay new mail to all group members'.
* [CHD-3976] [Worklists/Import/Mail] When importing CSV files on ticket worklists, records may now be matched on the 'ID' or 'Mask' columns.  Previously records were required to match exclusively on the mask column.
6.8.6-checkpoint
Merge branch '6.8.6' into stable