Add support for "away-notify" capability (http://ircv3.atheme.org/extensions/away-notify-3.1)
Add support for "account-notify" capability (http://ircv3.atheme.org/extensions/account-notify-3.1)
Add support for "extended-join" capability (http://ircv3.atheme.org/extensions/extended-join-3.1)
Don't bother negotiating UHNAMES or NAMESX using PROTOCTL if we have already enabled the userhost-in-names and multi-prefix capabilities with CAP
Don't bother asking for TSIRC using the TIMESTAMPEDIRC command if we have negotiated it using CAP

Rename "tsirc" capability to "dfbnc.com/tsirc" as a non-standard capability

From a DMDirc point of view, capabilities probably need exposing through the general interface somehow so that if (for example) away-notify is enabled, the client doesn't still send lots of WHOs.

Change-Id: Ice7a8ceae5595a364881e5a1fbe2d7fbdef9a639
Reviewed-on: http://gerrit.dmdirc.com/2544
Reviewed-by: Chris Smith <chris@dmdirc.com>
Automatic-Compile: DMDirc Build Manager