chanserv/akick LIST: Require +A even given PUBACL

AKICK reasons and expiration might be considered private information;
the op-only part of the reason certainly is.

Note that it's still possible to see a list of AKICKed people via
/cs flags #channel +b while PUBACL is set.
chanserv/info: viewing PRIVATE info needs +A

The rationale is that access to private information about a channel
requires the +A flag; PRIVATE and PUBACL allow making adjustments to
what is considered private. With PRIVATE set, most info requires +A.

However, on channels with PUBACL set, we display the founder and
successor to everyone as they could just check the ACL themselves
anyway.
chanserv/info: Show PUBACL among channel control flags
chanserv/info: Oops, fix compilation breakage
chanserv/taxonomy: Metadata isn't covered by PUBACL

This is consistent with chanserv/info: metadata is public by default
unless the PRIVATE flag is set.
NEWS: add more updates
Set the default to only roll/calc once if not specified.
libathemecore: update CTCP ABOUT.
nickserv/sendpass_user.c: Require the caller to know the user/email combination unless they have the user:sendpass priv. Don't leak information about if the mail was sent or not, as to not allow people to find user's emails by guessing.
nickserv/sendpass_user: Improve command success/failure output
README.md: modify IRC link

Unfortunately enough, GitHub doesn't support irc:// URIs in links, so
put something more helpful in the link text. Also add a webchat link.

Closes #12.