Sometimes bootstrapped BCES would fail for small samples. Fixed
Sometimes bootstrapped BCES would fail for small samples. Fixed

Sometimes, if the dataset is very small, the regression parameters in
some instances of the bootstrapped sample may have NaNs i.e. failed
regression. I still do not understand the exact nature of these failures.
It could be something very simple. In any case, I implemented a fix
that removes NaN fit results from the final bootstrapped sample.

rsnemmen/BCES