Elliptic functions update



James Amundson has graciously added me to the maxima developer list; I
hope his trust has not been misplaced!

As my first act, I'd like to import my elliptic functions package in
place of the existing src/ellipt.lisp file.  This will cause an
incompatibility because the function names have changed.  William
Schelter had named the functions sn, cn, dn.  They're now called
jacobi_sn, jacobi_cn, etc.  Other name changes have occurred as well,
but I think the names and functionality match what Macsyma does.

If there are no objections, I'll check this in soon.

Ray