Fixed BoolNotView not conforming to its interface.

BoolNotView's nextValue and previousValue do not conform to its interface. nextValue should return Integer.MAX_VALUE when it is out of values, but currently it is returning Integer.MIN_VALUE for such cases. Likewise, prevValue is returning the wrong value. As a result, the following program will be stuck in an infinite loop.

```java
public static void main(String[] args) {
    Solver solver = new Solver();
    BoolVar a = VF.bool("a", solver);
    BoolVar b = VF.bool("b", solver);
    solver.post(ICF.arithm(a, "+", VF.not(b), "=", 2));
    System.out.println(solver.findSolution());
}
```