#4762 Expression being printed differently depending on SIMP flag

[David Scherfgen]

Compare how these two expressions print:

:lisp (setq $A '((MTIMES SIMP) ((RAT) -1 3) ((MPLUS SIMP) 1 $X)))
:lisp (setq $B '((MTIMES SIMP) ((RAT SIMP) -1 3) ((MPLUS SIMP) 1 $X)))

(%i1) a;
(%o1) (-1*(x+1))/3

(%i2) b;
(%o2) -((x+1)/3)

Why does printing depend on the presence of a simp flag?

There are lots of places in Maxima where literal '((rat) 1 2) expressions are passed into functions like add or mul that expect their arguments to be simplified. These should probably all be fixed.