BAN: Don't schedule check_klines for 0 seconds in the future.

When receiving bans from a bursting server, if kline_delay is set to 0
(the default), rb_event_addonce will be called to schedule an event for
0 seconds in the future. While this works fine for the fallback
rb_event_run function, the epoll implementation ends up scheduling a
timerfd for the event in the past, which is then never executed.

While fixing this, I also made rb_event_add and rb_event_addonce reject
attempts to add events scheduled for 0 seconds in the future; they're
instead rewritten to run 1 second in the future.
chmode: Check mlock when a local oper changes cmode +L/+P.

This check was erroneously removed when fixing /mode #channel f when +f is
mlocked. Mlock checks were restricted to the places requiring chanops
(other than viewing +eI lists); cmode +L/+P do not require chanops, but
still constitute a mode change that must be checked against mlock.
doc/sasl.txt: drop dead links, add links to IRCv3 spec and relevant SASL RFCs
doc/sasl.txt: forgot to wrap lines and sort references
Removed comment from src/modules.c that states certain function were moved into a file that no longer exists. (Circa ~2002)
Merge pull request #70 from grobe0ba/master

Remove incorrect comment regarding location of functions in src/modules.c
Fix crash when there are two blacklist hosts without intervening reason.

This is invalid configuration; the first host is supposed to be ignored.
Explicitly pass the current time to deactivate_conf().

Some places depend on the ban not being destroyed.
server: Remove two dead stores.
server: Don't read beyond the bounds of ServerInfo.ip and ServerInfo.ip6.
Gitignore vim swap files.
libratbox: Add comment that case fallthrough is deliberate.
bandb: Don't apply empty ban list when bandb starts sending bans.

When bandb sends the ban list, it first sends 'C', then all bans and
finally 'F'. Only when 'F' is sent is ircd supposed to apply the bans.
Because of a missing break, 'C' also did 'F', clearing the ircd active
permanent bans until bandb sent 'F'.

The effect is pretty limited because having bandb send the ban list via
/rehash bans is uncommon and most bans will be enforced when reset.
tools: Remove Hybrid 6 conversion tools.

Hybrid 6 is old enough that the conversion tools can go away now.
They are for I and K lines; the ircd.conf converter was already removed.

This removes compiler/analyzer warnings about these tools.
ban: Fix build breakage.

A normal 'make' did not rebuild m_ban.c even though dependencies had
changed.