alpha parameter for gamma distribution is not estimated

[NatJWalker-Hale]

Hi Carine,

Firstly, thanks for developing such a cool and useful tool. I have a query about incorporating rate variation among sites. When I run pcoc_det.py with the option --gamma and --no_cleanup, I can see from the bpp output in the directory Estimations that rate variation is being accounted for. However, it appears that alpha is set to 1, instead of being estimated which would be the desired behaviour. Is there a way to modify the script so that alpha is estimated instead?

Cheers,

Nathanael