New Crowdin updates

update strings

reduce recommended bcrypt cost to the lowest allowed value

Two objectives:

1. Reduce thundering-herd effects on server restart (a cost of 4 should be
approximately 1 millisecond of CPU time per reconnecting client)
2. Speed up mobile reattach as much as possible (see also #1420)

fix #1490

UBAN and some other operator changes (fixes #1447)

Track channel join times, use them to optionally enforce history access
restrictions

New Crowdin updates

Improve auditability of sensitive operator actions

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

stopgap documentation update for SASL

See #1488

fix always-on expiration checks

checkAlwaysOnExpirationNoMutex was respecting registered status, but
always-on clients were not considered registered at the time of the
initial check, so they were being created regardless of expiration.

initial work on #1483

Add the new utf8-only cap, disallow non-utf8 when websockets are enabled

fix #1479

fix #1476

clarify productionizing guide