Draft: SNR Series Wrapper Class

This MR attempts to apply strong typing, remove all GetSet code and replace it with the relatively simpler PyMemberDef method of accessing PyObject attributes.

In it's current state, an error occurs during the second iteration of the postcohtable_wrapper object creation, but segfaults at the third numpy array object creation on the second postcohtable_wrapper creation, at _postcohtable.c:466