Allow setting the minimum TLS version

Prevent LUSERS stats from getting out of sync when modes are
modified on offline clients.

Allow snomasks to be added via oper config block, even if the oper
doesn't have `ban` or `snomasks` and therefore can't add snomasks
on their own.

Clean up channels during unregistration if necessary.

Warn users that NS UNREGISTER doesn't give them a "do-over";
the account name will remain reserved.

UBAN ADD and DEL need to produce snomasks and loglines

Document permissions structure of CS AMODE

CS INFO with no arguments should list your registered channels

Implements the new `CHATHISTORY LISTCORRESPONDENTS` API.

See #1603

1. Use FAIL instead of WARN
2. Use NICKNAME_RESERVED instead of ACCOUNT_REQUIRED
3. Don't send 433 at all for registered clients, just send the FAIL

List IRCv3 CAPs in `NS CLIENTS LIST` output

Send a WARN NICK ACCOUNT_REQUIRED on attempt to take a reserved nick

All truncation must be made UTF8-safe.

AWAY status should be tracked per-session:

1. With auto-away enabled, away status is aggregated across sessions
   (if any session is not away, the client is not away, else use
   the away status that was set most recently)
2. With auto-away disabled, we get the legacy behavior where AWAY
   applies directly to the client

Implement the new bot mode spec:
https://github.com/ircv3/ircv3-specifications/pull/439

RELAYMSG should respect mutes

Improve error message for CS TRANSFER

PerstentStatusMandatory should display as "enabled", not "mandatory",
in the context where it refers to a user-chosen setting.

Allow chanops to delete channel messages from history

Handle panics in rehash, even if it was triggered by SIGHUP

Implements #1577, but the issue should remain open until we clean up
the debugging loglines.

Fixes #1064.

make PASSWORD an alias for PASSWD in nickserv

1. Send COMPLETE_CONNECTION_REQUIRED instead of DISALLOWED
2. Include the account name in all FAIL messages

ERR_INVALIDMODEPARAM should take both the mode and the invalid parameter
as arguments.

As of #1483, websockets entail enforce-utf8, so there's no need
to check globalUTF8EnforcementSetting when handling websockets.

Improve debuggability of some config deserialization errors

1. Text and binary frames are accepted
2. Text frames are sent by default
3. Binary frames are sent to clients who negotiate `binary.ircv3.net`
4. Non-UTF8 data is not accepted (enabling websockets still enables UTFONLY)

ZNC playback LIST was panicking when history was disabled,
and possibly in other cases

If history is disabled, disable the history CAPs

Fixes #1510