Fixed computation of chi1 and chi2 by using tilt
Multiplied np.cos(samples['tilt1']) and np.cos(samples['tilt1']) to samples['a1'] and samples['a2']. Tested for S200115j, which gives HasRemnant=0.6301763423816128. The mean value of the chi1 posterior for this event is -0.1593135142617203, compared to -0.65294266 from the recovered template