py-newline-and-indent.  These ought to get picked up by the mapcar
that follows; any existing binding to newline-and-indent gets shadowed
to py-newline-and-indent.

This will break some people who, e.g. bind C-m or C-j to newline but
still want these bound to py-newline-and-indent in Python mode.  On
the other hand, the forced binding pisses off Emacs diehards.  So
consider this experimental and see if any tall Dutch guys complain :-)