Enhancement to termplot()

I'd like to make the following change to termplot():

Add panel=points as an extra parameter.

(I foreshadowed this when I submitted problem #6327, and offered a fix
that, in default of anything better, I assume will be made or has been
made.)

I added a smooth= option, and fixed the bug at that time (a search of
bugs.r-project.org finds it in Models-fixed).  The suggested
fix didn't quite work, but a modification of it did.

BTW, for people who don't know, you can usually find help pages for
R-devel linked at the R web page, allowing you to check if things have
been changed.  At the moment it hasn't caught up with the reorganisation
of the base packages.

	-thomas