#2416 integrate changes k[0] --> k(0)

[Barton Willis]

(%i1) x * (x^2 + k[0])/(1 + x^2);
(%o1) (x*(x^2+k[0]))/(x^2+1)

(%i2) integrate(%,x);
(%o2) ((k(0)-1)*log(x^2+1))/2+x^2/2

First reported by David Ronis on the mailing list (http://www.math.utexas.edu/pipermail/maxima/2012/028989.html)

[Barton Willis]

The bug comes from subst10 (defined in sin.lisp). A possible fix is
to change (atom ex) to ($mapatom ex).

(defun subst10 (ex)
(cond ((atom ex) ex)
((and (eq (caar ex) 'mexpt) (eq (cadr ex) var))
(list '(mexpt) var (integerp2 (quotient (caddr ex) *d*))))
(t (cons (ncons (caar ex))
(mapcar #'(lambda (c) (subst10 c)) (cdr ex))))))