This affects /TOPIC, /INVITE, and a few others.

As of 3dc5c8de78, the PROXY-before-TLS proxy line
and any proxy information carried in X-Forwarded-For
do not count as the "first line", so an additional
client-supplied PROXY line would have been accepted.

fix #994

fix #952

Hide +i users from WHO * queries.

Construct a hash set of the user's channels and check that rather than
querying channel membership, to reduce the number of locks that need to be
acquired.

simplify listener rehash logic

new recommended default: proxy allowed from localhost

use 8097 as the example websocket port

Fixes #990.

fix #982

fix #983

fix #985

websockets implementation

use shorter batch IDs

Add ChanServ and NickServ LIST commands.

These commands search the registered nicknames/channels for ones
matching the provided regex, or return the entire list.

Only operators with chanreg (for ChanServ) or accreg (for NickServ)
capabilities can use LIST.

make +i the recommended default usermode

Add support for default user modes. #942

Add default-user-modes configuration to conventional.yaml.
Fix comment on DefaultUserModes.