move build.yml to .builds/
Upgrade dependencies
Upgrade to gopkg.in/irc.v4
contrib/clients: reference read_marker.py for Weechat
Use ratified extended-monitor cap name for needAllDownstreamCaps

Fixes: 6ad3dcc39699 ("Use ratified extended-monitor cap name")
Use ratified extended-monitor cap name

References: https://github.com/ircv3/ircv3-specifications/pull/508
downstream: stop sending HTTP OPTIONS request on WEBPUSH REGISTER

We were sending a test notification later anyways. Let's just do
that to check that the endpoint accepts our messages.
Make the auto-away functionality configurable
Add build tag for modernc/sqlite driver
downstream: drop downstreamConn.unmarshalEntity{,Network}
config: drop multi-upstream-mode
doc: drop multi-upstream mode bits
irc: drop needMarshaling from applyChannelModes return values

Not used anymore.
upstream: use forEachDownstreamByID to forward RPL_AWAY

It's a reply to a command. If possible, avoid broadcasting it to
all connected clients.
upstream: remove heuristic to marshal nick in errors
downstream: drop downstreamConn.marshalEntity

This is a no-op.
downstream: drop downstreamConn.marshalMessage

It's a no-op.
downstream: drop downstreamConn.marshalUserPrefix

This is now a no-op.
downstream: drop downstreamConn.unmarshalText

It's unused.