Remove an orphaned function.

userStatusChange used to add or remove users
from the online list, and optionally notifying of the change.
This is currently done from the xmpp module directly.
Escape variables in messageAddInfo() and userFormat()

Room and nick names can contain raw markup.
messageAddInfo() now takes an optional variables
object and a string with placeholders. Markup
in variables is escaped before printing.
Move formatTime and messageCreate to visual.js

It makes sense to have all the rendering code
in one place. This did require removing the message.id
counter, but we were not using that anyway:
The DOM references are stored in the message array when
added, so we don't need the unique ID attribute.

Also, renamed renderText to formatBody,
and messageCreate to formatMessage for consistency.