#25 ER: Add Context Menu to User List

[Christoph Daniel Schulze]

When a user on the user list is right-clicked, a popup
menu should appear detailling the available actions for
that user. That could include a WHO, WHOIS, Private
Chat (which should be the default action when
double-clicking), CTCP VERSION, CTCP USERINFO, CTCP
CLIENTINFO, CTCP PING, CTCP TIME and operator actions
if the Jaic Wain user is the channel operator.