[Code Cleanup]
Merge branch '6.2.4' into 6.3
* [CHD-3276] [Tasks/Usability] On the profile page of a task, the Comments tab is now the default. It is also shown before the Activity Log tab.
* [CHD-3275] [Mail/Attachments/Usability] Workers may now upload multiple files at once when using an HTML5-compatible browser (e.g. Chrome).  Previously, each file had to be attached individually using the file dialog.  Multiple files may be selected by using CTRL/CMD, or SHIFT, when left-clicking.
* [Attachments/Performance] Performed some optimizations on the way attachment link UUIDs (universally unique IDs) are stored and indexed in the database.
* [Attachments/Scalability/Replication] Modified the way attachment links are inserted into the database so they are compatible with binary logging. Previously, these queries used MySQL's UUID() function in INSERT statements. This is technically fine, since the UUID value isn't used in any other tables; however, MySQL may still record error_log entries about using dynamic functions in inserts when binary logging is enabled.  These inserts are now done in two steps, with a SELECT UUID() and then an explicit INSERT value for the 'guid' column.
* [Code Cleanup/Session] Fixed a bug where all sessions were prematurely logged out if a worker reset their credentials from Settings->Security.
* [CHD-3282] [Mail/Usability] When merging tickets from a worklist, the merge confirmation popup will now auto-focus the 'OK' button.  This doesn't interrupt keyboard shortcut workflows.
Merge branch '6.2.5' into 6.3
[Code Cleanup]
* [CHD-3280] [Virtual Attendant/Custom Fields] Virtual Attendant behaviors may now set cross-record custom fields. For example, a ticket behavior can also set custom fields on the sender and their organization. This enables many new VA workflows. You could now have a 'new message' behavior set a date custom field on the sender's record to keep track of their latest incoming message.  This could be used for sales, marketing, or even to throttle auto-replies.  For another example, VAs could automatically manage 'unsubscribe' functionality by setting a 'do not contact' custom field on sender addresses when they reply with 'remove me'.  Previously, all this advanced behavior required scheduling macros on other records, which didn't run immediately, and also left a lot of one-use macro clutter in Virtual Attendants. This new solution is much simpler and more powerful.
6.3-dev checkpoint