**Support problem:**
Given a bilinear support, generate a spline surface as close to the support
as possible staying strictly above the support.

The user can specify: degree and smoothness of the spline.

In the examples below, the support and its control points are in green and
the solution surface and its control points are in red.

Semi-random bilinear support |
Degree 3 Bezier surface spline solution |

2-D bilinear hat |
Degree 3 Bezier surface spline solution |

2-D bilinear pyramid |
Degree 3 Bezier surface spline solution |