Fix incorrect description of channel ownership in NS INFO

Warn users that NS UNREGISTER doesn't give them a "do-over";
the account name will remain reserved.

CS INFO with no arguments should list your registered channels

List IRCv3 CAPs in `NS CLIENTS LIST` output

PerstentStatusMandatory should display as "enabled", not "mandatory",
in the context where it refers to a user-chosen setting.

make PASSWORD an alias for PASSWD in nickserv

Improve auditability of sensitive operator actions

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

Fixes #1380

Enhancements to NS SUSPEND, including stored metadata and the ability
to list suspensions

CLIENTS LIST shows information about clients attached to a nick.
CLIENTS LOGOUT allows individual (or all) sessions to be logged out.

SESSIONS is now an alias for CLIENTS LIST.

Fixes #1072.

These commands search the registered nicknames/channels for ones
matching the provided regex, or return the entire list.

Only operators with chanreg (for ChanServ) or accreg (for NickServ)
capabilities can use LIST.

Or try to, anyway