Improvements of IntVar Views

[arnaud-m]

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}