Don't leak copies of messages.
  New member CFile::delete_file( path );
  Fixed compilation failure in debug-build.
  Use CFile::delete_file() rather than unlink().

  This is basically for logging purposes as I rework some of the
 message-handling.
  Added stub CScreen::choose_string.

  This is part of overhauling the TAB-completion code to resolve
 ambiguity.