LHCbMath: backport some developments (and fixes) from ostap-standalone

1. There is a fix for Lomont' next_float/next_double method. Other functors from this file were also rewritten properly.
2. Bernstein polynomials:

• improve numerical stability of polinomial division
• remove gcd (better to keep it in python using proper efficient divmod from C++)
• add functions ( splits, control polygon, convex hulls, crossing points...) that allow easy and efficient implementation of root-finding in python

3. B-spline

• improve numerical stability
• add knot insertion using Boehm's algorithm
• add functions (split, knot inserions, contorl polygons, convex hulls, crossing points) that allow easy and efficient implementation of root-finding in python
• add spline VDM approximatinon
• add spline interpolation
• add Berstein -> BSpline conversion
• make some internal algorithm "visible" and usable outside b-spline ( de Boor, Boehm, ...)

4. Add few useful functions&objects into LHCb::Math namespace