Fix tau when calling tca

[YushaLiu]

I got a question about tau. I called tca with tau = 0.05, but the returning model fit indicates that TCA is still estimating tau and not using the value I provided, e.g., the tau_hat component from the output is still the estimated tau that I would obtain by setting tau = NULL in the tca call. I'm using TCA_1.2.1. Could you please look into it?