Fixed bug in histograms with only one bar
Fixed bug in histograms with only one bar

The previous fix forced the single bar to appear
at 0. With p = 0, that is the right result for the
PSP histogram. However, with CV = 0 and q != 0,
that is incorrect for the mPSP histogram.

CWRUChielLab/JSNeuroSim,CWRUChielLab/JSNeuroSim,CWRUChielLab/JSNeuroSim