Add regression tests for bug 25

tests/sat/mod_repr.smt2

+;; produced by colibri.drv ;;
+(set-logic ALL)
+(set-info :smt-lib-version 2.6)
+
+(define-fun mod1 ((x Int) (y Int)) Int (ite (< 0 y) (mod x y) (+ (mod x y) y)))
+
+
+(define-fun in_range1 ((x Int)) Bool (and (<= 1 x) (<= x 100)))
+
+
+(declare-const x Int)
+
+;; Assume
+  (assert (in_range1 x))
+
+(assert (not (in_range1 (mod1 (+ x 1) 100))))
+(check-sat)
+(get-value (x))