Improvements of IntVar Views

Let x be a integer variable. The following views are available:

- scale view: s(x) = a*x (a >= -1)
- minus view: m(x) = -x
- offset view: t(x) = x + b

Here are two natural improvements
- [ ] extend the scale view for any a.
- [ ] propose an affine view: f(x) = a*x + b

Experienced with choco-solver-_*{4.0.6}*_

No source file, test, or entry point is named. Start by locating the existing IntVar scale, minus, and offset views, then determine the intended behavior and constraints for negative scale factors and the affine view. Done means the requested view improvements are implemented with coverage for the proposed cases.

Written by the indexing model from the issue text.