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

scripting API for IP bans

See discussion on #68.

add untracked x/sys/unix files

These should have been added in 66995cdfdf.
Forgetting this seems to be an ongoing problem.

make channel founder unkickable

fix #1259

Initial RELAYMSG implementation

See #1240

fix #1213

use utils.StringSet in more places

PONG param 0 should be server name

set up new development window

changelog for v2.3.0

remove dead code

fix #1254

fix critical bugs in 2.3.0-rc1

fix #1248

remove stray references to timeout enforcement