added option to call Cauchy hyperpriors on BD rates under any model
added option to call Cauchy hyperpriors on BD rates under any model

Cauchy hyper priors were previously used only with -fixShift option
enabled. Now they can be called with the option -cauchy (useful e.g.
when assuming a number of shifts with -mL, -mM options)

dsilvestro/PyRate,dsilvestro/PyRate,dsilvestro/PyRate,dsilvestro/PyRate