Change back to polling mode since the multi-select isn't reliable on all

platforms.
Move topic bar to above status bar so the terminals scrollback is usefull.
Fix nick completion...
   1) The "Matching nicks" string was being borked (was using nick[i]
      instead of this.nick[i]
   2) input_buffer manupulation is now done only by the screen object as
      it should be... no more passing the whole input buffer
Nick changes now only remove the first char of the new nick if it's a :
  (Cyan: check me on this one)
Fix the arg copying FIXME
There's still an issue in screen.print_line() where a NOTICE can cause
the topic line to be duplicated in the output area.