Features:

• Option to turn off or on Resume chat functionality.
• Reopen chat permission in back office.
• If chat is closed, operator won't be able to send messages untill it's reopened. What user reopened the chat also is logged.

Bugfixes:

• Footprint was not detected if chat was started from proactive chat message.
• Messages scroll was lost sometimes during tab's switching.
• Don't blink title if textarea is active.

execute doc/update_db/update_37.sql and follow standard upgrade instructions