Probe template not accepted if not numpy array

In score_sample_template from abstract_classes.py there is a check that the data is "valid" (here).

It checks that the template in the samples is a Numpy array and is not empty. But in GMM for example, the templates are objects (GMMStats) and all the samples are considered "invalid" and ignored silently.

We could either remove the check or implement a way of detecting non-Numpy objects and allow those unconditionally.