first draft of atheme migration code

1. Avoid undefined behavior of time.Time{}.UnixNano()
2. Times should be compared with Equal()

fix #1293

fix #1303

auditorium mode

actually enable the +T no-ctcp umode

ParseUserModeChanges and ParseChannelModeChanges already validate
that the modes are modifiable, so there's no need to repeat it here.

fix #1295

fix non-linux builds

output unix socket credentials where applicable

thanks @ajaspers!

pointless optimization

fix #1284

fix #1277

attempt to fix #1282

fix #414

run irctest in travis

fix NICK responses for SANICK

Add +M (only registered/voice can speak) chanmode.

Update MANUAL.md

Add chanmode preventing speech to error message.

Fixes #1182.

Add NickServ "CLIENTS LIST" and "CLIENTS LOGOUT".

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.

fix #1240

See #1240.

fix websocket listeners with proxy-before-TLS closing on bad PROXY lines

anything other than a (net.Error) with Temporary() == true
is treated as a fatal error that causes the http server to exit

pass the require-sasl message through from the script