Interpolation at points

Topics
	The point interpolation (generic) module
	The (generic) point interpolation module.
	Lagrange point interpolation
	Field interpolation and derivation to arbitrary points.

Detailed Description

This module is split in two, for backward compatibility:

1. Lagrange point interpolation (former version)
2. Generic point interpolation (with more diversity in schemes)

Todo:

MCO: do a proper integration of "Lagrange" point interpolation in the new framework. But before I need to test for efficiency matters.