set_input_shape in public bases

[BalzaniEdoardo]

Copying mine and @billbrod comment to PR #276 regarding the set_input_shape of concrete classis in basis/basis.py.

I think we've already discussed this, but there's no way to have super().init() initialize both super classes?

My response:

This modification is quite complex and requires some precision, so we can leave it a future PR.
The method that in theory can work is the first one super().init() however, for this to work, for all the classes inheriting directly AtomicBasis and Basis, we need to invert the inheritance order.

This also doesn't work directly, because AtomicBasis is using some parameters that are defined at basis initialization.

I think this all can be smoothed out but requires precision and a dedicate PR. I'll add it to an issue