copy method
Copies another name
object to this instance.
Implementation
@override
SplineCurve copy(Curve source) {
if(source is SplineCurve){
super.copy(source);
points = [];
for (int i = 0, l = source.points.length; i < l; i++) {
final point = source.points[i];
points.add(point.clone());
}
}
return this;
}