Had to replace a few lines to ensure proper writing of prior fluxes to the...

Had to replace a few lines to ensure proper writing of prior fluxes to the files. Until now, prior fluxes 
were retrieved from a savestate.nc file (and erroneously, the poterior was read by default) while the "old"
method to provide priors was as unscaled fluxes (all multipliers equal to 1.0). This behavior is now back.