user visible email errors, email timeouts

pin docker base image to alpine 3.13

May fix #1726 (broken build on dockerhub)

fix missing disconnect sno help text

update draft/register -> draft/account-registration

fix #1738

Fixes #1740

See #1659

Fix error message for privileged NS PASSWD on a nonexistent account

add a debug logline for client read errors

May help clarify TLS configuration issues, possibly others too

support systemd notifications

fix UBAN ADD of masks (k-lines) not killing clients

Fixes #1733

DISCONNECT Sno for always-on and/or multiclient

fix #1722

fix #1731

CHATHISTORY INVALID_TARGETS was missing the subcommand parameter

Include nick in ERR_LISTMODEALREADYSET and ERR_LISTMODENOTSET

Validate operator vhosts against the configured (or default)
vhosts.valid-regexp

Allow +v users to talk in +R channels.

fix #1714

Fix a panic if the operator class title is empty

Fixing the AUR package link in the README.md file

Show real IP in WHOWAS to opers with ban capability.

fix #1703

update docker readme

It could be the real IP or the proxied IP.

`WHOWAS :` should return an error numeric instead of an empty response

fix #1696

use ergochat/irc-go instead of goshuirc/irc-go

add a FAQ entry for global notices