Re-added B-spline transformation for non-linear RT alignment in MapAlignerIdentification

Including updated tests.
> 1. I think it didn't work with BSpline2d because the "eval" method there isn't declared const.

Should be fixed in #1051

> 2. ..

see @timosachsenberg response

> 3. For the parameter, what's the point of declaring it as const if it's passed by value?

Even the parameter is passed by value this still ensures that the programmer is not able to alter the value of the parameter.