New wrappers for SciPy interpolators

[fandreuz]

It would be useful to add new wrappers (i.e. subclasses of Approximation for interpolators in order to improve usability from EZyRB.

Here you can find an example, the EZyRB wrapper for RBF.

Each wrapper should contain the methods fit and predict to allow training and using the interpolator.

Some resources about scipy.interpolate:

• GitHub;
• API reference;
• SciPy Tutorial