* Makefile: Add dependencies between targets

* Implement draft/message-redaction for channels

Permission to use REDACT mirrors permission for 'HistServ DELETE'

* Error when the given targetmsg does not exist

* gofmt

* Add CanDelete enum type

* gofmt

* Add support for PMs

* Fix documentation of allow-individual-delete.

* Remove 'TODO: add configurable fallback'

slingamn says it's probably not desirable, and I'm on the fence.
Out of laziness, let's omit it for now, as it's not a regression
compared to '/msg HistServ DELETE'.

* Revert "Makefile: Add dependencies between targets"

This reverts commit 2182b1da69.

---------

Co-authored-by: Val Lorentz <progval+git+ergo@progval.net>

* implement draft/pre-away
* clean up some subtleties in auto-away aggregation.
* consistently apply auto-away only to always-on
* `AWAY *` should not produce user-visible changes wherever possible

* Add ACCEPT-tracking functionality (authorizing users to send DMs
  despite +R or other applicable restrictions)
* Sending a DM automatically accepts the recipient
* Add explicit ACCEPT command

Fixes #1740

Transition most "is an operator" checks to require a specific operator
capability

strip local_ from oper capab names, also consolidate unban into ban

Explicit quit and ping timeout behave the same way,
but reattach after abandoning/losing the previous session
(without the break being detected server-side) is more aggressive
about replaying missed messages, at the cost of potential duplication.

* Fix #679 (borked reply to `JOIN #chan,\r\n`)
* Replace invalid error parameters with *'s in various places
* Fix PART with no message sending an empty trailing parameter to the channel
* Fix some error responses not getting labeled

Some clients seem to automatically poll for channel state

1. Remove leaveClientIdle (unused)
2. s/leaveClientActive/leaveClientIdle/
3. make ISON a leaveClientIdle command (some clients send it periodically
   if a /msg window is left open)