scipy.isnan() and scipy.isinf() no longer exist

[albertotonda]

In the code, there are a few occurrences of scipy.isnan() and scipy.isinf() (for example, around line 89 of file bases.py). They no longer exist, but they can be easily replaced with the corresponding numpy functions, e.g. np.isnan() and np.isinf(). I replaced them myself in my local install, and now it seems to work.