Add iterators to newsearch, along with an example channel iterator function.

Add iterators to newsearch, along with an example channel iterator function.
Yey! First class functions!!

Example:
  (any (channeliter x) (match (var x) #twilight*))

Roughly equivalent to:
  example = lambda nick: any(lambda x: fnmatch.fnmatch(x, "#twilight*"), nick.channels)
  for nick in networknicks:
    if example(nick):
      print nick