New classes for spline interpolation tables

New classes for spline interpolation tables

Quadratic and cubic spline tables can be constructed either
from analytical functions or numerical vector input, and they
can contain an arbitrary number of functions as multi-tables.
Spacing is optimized to achieve the requested precision.
To make the class more generic it works with functions and
derivatives, and avoids worrying about swapping signs to get
forces. The interpolation functions are templated and will also
work with SIMD, without exposing any table internals.

Change-Id: If75f52b0601ad4b396d3cef74b5bbbe81ba91753