Revision 172

Made sure that num_cmp, fun_cmp and str_cmp return an
answer evaluator when used in scalar context.  In other words

$ans_eval = num_cmp(234);

will now work as expected -- you will get one answer evaluator which
checks whether the answer is 234.

Previously you had to write:

($ans_eval) = num_cmp(234);

or else you would have the numeral 1 placed in $ans_eval since
that is how many answer evaluators were created.