Export internal functions for a new R package

[mikeroswell]

Working on a small R package that has strong both conceptual and functional overlap with SpadeR; hoping we might resolve an emerging "dependencies" issue with you.

In a few places we would like to internal SpadeR functions:
SpadeR:::Bt_prob_abu, SpadeR:::Chao_Hill_abu, SpadeR:::Hill, SpadeR:::Chat.Ind

We're not using the analogous incidence-based versions (_inc and .Sam) for now.

Would you be willing to either export these functions in an update to the SpadeR package on CRAN, or export them in a development branch of the package on GitHub so that we could import named, external, fully documented functions from SpadeR? We're new to package building but it's our sense that something along those lines is in keeping with recommended practice, while both importing internal functions and copying source code are not.

Thanks so much for your consideration!