upgrade to go 1.18, start using generics

DEFCON 4 and lower were blocking SAREGISTER. This is wrong; admins should be
allowed to make new accounts even under DEFCON (this may be needed
specifically to work around the DEFCON restriction).

* Fix #1911 +s channels don't appear in /list even though on the channel

* use channel.HasClient instead of custom iterative checker

bump recommended CHATHISTORY limit to 1000

distrib: refine OpenRC init scripts

- Add logging to init script
- Add delay so OpenRC realises if we crashed quickly b/c of e.g. bad config
   file
- General cleanups (like supporting multiple instances, style changes)

This should make it a lot easier to see what's going wrong when something
breaks.

Bug: ergochat/ergo#1914
Signed-off-by: Sam James <sam@gentoo.org>

Discussed with emersion, this is the value used in soju and it works fine.

use exact integer parsing for znc.in/playback

fix #1895

Update help of REGISTER and VERIFY commands

Include server start time in INFO output.

fix #1906

Having the 'samode' capability made all KICK commands privileged. This appears
to have been introduced unintentionally by 42316bc04f and I can't find
any discussion of a rationale. Since this goes against our policy that all
ircop (as opposed to channel founder) privileges must be invoked explicitly
(e.g. SAJOIN, SAMODE), remove this.

bump irc-go to v0.1.0

fix #1896

Don't allow any new uses of 0 as a nickname, since it conflicts with
the use of 0 as a placeholder for account name in WHOX.

show arbitrary IP in WHOX

fix #1901

AMODE +v should allow you to join a +i channel

Add FAQ about WebIRC and secure clients

fix #1898

NS SAREGISTER would fail due to a nil dereference of `client`;
add two safeguards against this.

distrib: add OpenRC init scripts

This extends #1650 to cover WHO as well as WHOIS

Signed-off-by: Sam James <sam@gentoo.org>

Written originally for Gentoo but should work
on Alpine and other OpenRC-consuming distros too.

Signed-off-by: Sam James <sam@gentoo.org>