Add optional support for rfc1459 and rfc1459-strict casemappings

fix login throttle handling

We were checking the login throttle at the beginning of every SASL
conversation. This had several problems:

1. Pidgin (on Windows?) tries every mechanism in order, regardless of
the CAP advertisement. It would use up the default throttle allowance
trying unsupported mechanisms like CRAM-MD5.
2. The throttle was actually checked twice for AUTHENTICATE PLAIN
(once at the start of the conversation and once in AuthenticateByPassphrase).

The general pattern here is that we should check the throttle every time we
do something "expensive" (bcrypt verification, send a reset email) or
"dangerous" (anything that could lead to a bruteforce attack on passwords).
Therefore, delete the check from the AUTHENTICATE handler, and add one at
the beginning of the SCRAM conversation to replace it.

fix deadlock on channel state mutex

add i2pd b32 address directions

Fixes #1686

fix #2144

fix #2142

add a config switch to accept hostnames from WEBIRC

RPL_NAMREPLY should send = for normal channels and @ for secret channels,
as per Modern docs.

See #1686; this allows i2pd to pass the i2p address to Ergo, which may be
useful for moderation under some circumstances.

Allow specifying TCP4 or TCP6 for outgoing email sending, or choosing a
specific local address to send from.

fix #2139

Database backup filenames contained a colon character, which is disallowed
on Windows; use period instead

fix #2135

* fix #2133

Don't record NICK and QUIT in history for invisible auditorium members

Handling of reserved nicknames is special-cased due to #1594, but we want to send
ERR_NICKNAMEINUSE if the nickname is actually in use, since that doesn't pose any
client compatibility problems.

* fix #2129

Don't print the values of environment variable overrides, just the keys

* fix unit tests

fix #2130

We load registered channels unconditionally; reloading them again on rehash
is incorrect. This caused buggy behavior when channel registration was
disabled in the config, but some registered channels were already loaded.

* Gracefully handle NS cert add myself <fp>

A non-operator with the nick "mynick" attempts to register
a fingerprint to their authenticated account.

They /msg NickServ cert add mynick <fingerprint>

NickServ responds with "Insufficient privileges" because
they've accidentally invoked the operator syntax (to action
other accounts).

This patch allows the user to add the fingerprint if the client's
account is identical to the target account.

Signed-off-by: Matt Hamilton <m@tthamilton.com>

* Update nickserv.go

Compare the case-normalized target to Account()

---------

Signed-off-by: Matt Hamilton <m@tthamilton.com>
Co-authored-by: Shivaram Lingamneni <slingamn@cs.stanford.edu>

* implement SASL OAUTHBEARER and draft/bearer
* Upgrade JWT lib
* Fix an edge case in SASL EXTERNAL
* Accept longer SASL responses
* review fix: allow multiple token definitions
* enhance tests
* use SASL utilities from irc-go
* test expired tokens

pull out max parameters constant in isupport impl

upgrade to go 1.22

fix #2123

Add a configurable limit on realname length

* Add caddy reverse proxy websocket example

* Use consistent hostname for caddy reverse proxy

* Explain reverse proxy setup for websockets

* Update MANUAL.md

Clarify that we only support `X-Forwarded-For`

---------

Co-authored-by: Shivaram Lingamneni <slingamn@cs.stanford.edu>

bump version and changelog for 2.13.0-rc1

add panic handler to async client/channel writes

See #2113 for motivation

fix #2114

Channels with slashes (or other relaymsg separators) in their names
were being falsely detected as relaymsg identifiers.

fix #2113

Persisting always-on clients was panicking if client X believed it was
a member of channel Y, but channel Y didn't have a record of client X.