Noise magnitude can be a function (not just a constant) in shc_lv_integrate

Noise can now be varied as a function of time (not state -this is additive diagonal noise) during integration.

shc_lv_ic() updated. Eta renamed to Epsilon. Desired A0 is now (again) set directly relative to zero, rather than relative to Beta. This may still change.

Lint warning fixes for shc_lv_passagetime_plot().

Signed-off-by: Andrew D. Horchler <adh9@case.edu>