The current default AnnounceInterval is too short, causing the
multicast domain to be flooded with NOTIFY announcements,
which may prevent other dlna devices from sleeping.
This change allows users to set the announcement interval,
and it's default value also increased to 12 minutes.
Even within the interval, rclone can still passively respond to
M-SEARCH requests from other devices.
Verify the http service listening address and the SSDP server
announcement address to prevent accidental listening of IPv6 addresses
that do not support dlna yet and may be globally accessible.
Unlistened addresses on the interface will also be filtered out of the
SSDP announcement to avoid misleading other services in the multicast domain.
YanceyChiewandNick Craig-Wood