multivariable kron_delta



The kron_delta function now takes two or more arguments--I committed new 
code, user documentation, and (regression) tests

Maxima 5.24post http://maxima.sourceforge.net
using Lisp Clozure Common Lisp Version 1.6-dev  (WindowsX8632)

(%i1) kron_delta(u,n,k);
(%o1)kron_delta(k, n, u)

(%i2) subst(k=n+1,%);
(%o2) 0

(%i3) kron_delta(a,b,-c) - kron_delta(-a,-b,c);
(%o3) 0

(%i4) kron_delta(a,a,a,a);
(%o4)  1


--Barton