Adds extra output from sampleWdMass when the '--details' flag is provided

Passing the '--details' flag to sampleWDMass now causes it to output additional files:
    wd.coolingAge: Cooling ages for every WD
    wd.logg: log(g) for every WD
    wd.logTeff: log10(T_eff) for every WD
    wd.precLogAge: The precursor log age for every WD

The mass and membership files names have been changes to '*.wd.mass' and '*.wd.membership'