proper get_prediction function for online inference

[Anna280]

initial/ first predictions from binary children should be drawn from the parents whose predictions comes from parents ect.

Current agnostic solution (mainly concerned categorical HGF) is to initialize the prediction in the binary state nodes. Therefore, parents initial predictions need to be equal.

[LegrandNico]

On way would be to copy the entire node structure and run a blank prediction step on that one without saving.