Safety commit: mechanisms for forward/back history added (two stacks for past and future), but total_spectrum not changing. Probably b/c need to be making copies of lists, e.g. x = y[:].
Safety commit: mechanisms for forward/back history added (two stacks for past and future), but total_spectrum not changing. Probably b/c need to be making copies of lists, e.g. x = y[:].

sametz/nmrmint