Print sliced expressions conjuncts asserts line by line

[SweetVishnya]

This merge makes printed sliced expressions more readable.

Now:

(assert (= ref!312542 (_ bv1 1)))
(assert (not (= ref!312501 (_ bv1 1))))

Instead of:

(assert (and (= ref!312542 (_ bv1 1)) (not (= ref!312501 (_ bv1 1)))))

Also, this is a workaround for recursion stack overflow during ASTs printing. I will propose a real fix later this week.