conversion to spatial orbitals

[RichRick1]

It seems like conversion of 2-body term from spinorbitals to spatial orbitals ends up adding values of alpha and beta spinors.
The problem is that such behaviour is inconsistent with the conversion of 1 electron integral to spatial basis -- instead of adding values of alpha and beta spinors, it returns just alpha part.

• check the behaviour of the to_spatial method in the api.py file. Make sure that return not the sum of spinors, but average.