Performs the basic concentration response curve fitting used in the 'tcpl' package. It is a substitute for the original tcplFit() function (and sub-functions) and allows a wider variety of concentration-response models. All of the models included in the 'BMDExpress' package are now part of this package, and the output includes a calculation of the bmd (Benchmark Dose or concentration) value.
copied from cf-staging / r-tcplfit2