A few small changes to make the PuTTY source base more usable as a

A few small changes to make the PuTTY source base more usable as a
basis for other terminal-involving applications: a stub
implementation of the printing interface, an additional function in
notiming.c, and also I've renamed the front-end function beep() to
do_beep() so as not to clash with beep() in lib[n]curses.

git-svn-id: http://svn.tartarus.org/sgt/putty@6479 cda61777-01e9-0310-a592-d414129be87e