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

Including updated tests.
Herb Sutter says: "Normally const pass-by-value is unuseful and misleading at best." (http://www.gotw.ca/gotw/006.htm)

I agree with that and don't see a good argument for adding the unnecessary "const" in the function declaration. The constraint it introduces - that the variable can't be modified in the function implementation - strikes me as both unnecessary and undesirable.