Support numpy arrays #57
Description
In addition to #56 adding direct support for scipy.sparse.csr_matrix we also should consider numpy ndarrays. In addition, this might enable us to use memory mapped arrays (There is no reason we need to elevate everything into ram at all times and memory mapped vecs (whatever the rust equivalent is) are not a bad idea for us.)
Somehow they're supported in pybind11 by simply using https://pybind11.readthedocs.io/en/stable/advanced/pycpp/numpy.html#arrays and I'd like to be able to use those as well. The benefits to this are fewer (or no) copy operations, and the possibility of relying on large fast NVMes for data instead of elevating everything into main system ram