Important update to Parameter-finding optimization function in non-uniform case

shc_lv_params() now uses fmincon() instead of fsolve() for for non-uniform case. This is in order to ensure that Alpha_i<=Nu_i*Alpha_i+1 constraint is maintained. Previous version could return parameter values that could result in Rho matrices with negative values in case where desired Tau values were different (possibly other cases too). The result is slower, but accurate. Other schemes are possible and may be investigated.

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