Modify par.glm.cov.R to include the snp recoded as the additive model
as a covariate in the lack-of-fit regression.
Re-created t/ref_data/sim2000.logistic.cov.lof.txt using par.glm.cov.R
using the modified lack-of-fit regression.
Merge branch 'add-covariate-to-lof' of github.com:guyrt/WFUBMC into add-covariate-to-lof