READ lets downstream clients share information between each other about
what messages have been read by other downstreams.
Each target/entity has an optional corresponding read receipt, which is
stored as a timestamp.
- When a downstream sends:
READ #chan timestamp=2020-01-01T01:23:45.000Z
the read receipt for that target is set to that date
- soju sends READ to downstreams:
- on JOIN, if the client uses the soju.im/read capability
- when the read receipt timestamp is set by any downstream
The read receipt date is clamped by the previous receipt date and the
current time.
git-svn-id: file:///srv/svn/repo/suika/trunk@781 f0ae65fe-ee39-954e-97ec-027ff2717ef4
9b1a5bd469