[API] add cpp for CubicSpline2d
[API] DLL macro added
[TEST] CubicSpline2d test split in several sections
[NOP] uncrustified
[NOP] uncrustified
[NOP] indention changed
[INTERNAL] template remnants removed
Merge pull request #810 from lars20070/feature/CubicSpline2d

[FIX] improvements/code fixes of cubic spline interpolation