primep matter



> 1) primep(2^31-1) hangs. I don't see why.

This is probably the same as my bug 852413 (factor(2^31-i) extremely
slow).  Please try my fix.

> 2) (defun primep...) tries to factor its argument which is very slow.
> 3) faster algorithhm is easily introducible:  ... replace native
> maxima's primep() in rat3c.lisp ...[with] primeq.lisp

Sounds like a good idea.

         -s