Use a new protocol message, 'resetidle' to inform Admin clients
whenever a user has done anything in a document view. This is a
message that Admin clients need to subscribe to.
Also add the current idle time for each document to the 'documents'
message.
To reduce protocol chatter, the idle time is updated at most once per
10 s.
Change-Id: I418e82b05048a3628f21dcd240ccd974b3a01356
Reviewed-on: https://gerrit.libreoffice.org/31653
Reviewed-by: Tor Lillqvist <tml@collabora.com>
Tested-by: Tor Lillqvist <tml@collabora.com>
