add make_split function
Function to create split data sets, if individual population sets become too large to simulate them efficiently.
refers to https://gitlab.rlp.net/mikrosim/mikrosim-primary/-/issues/18
Function to create split data sets, if individual population sets become too large to simulate them efficiently.
refers to https://gitlab.rlp.net/mikrosim/mikrosim-primary/-/issues/18