Groundhog for setting library dependency versions

[Frenzie]

This article explains some possible dependency issues with R.

http://datacolada.org/95

I'm not quite sure how relevant it is in this repo, but I thought it might at the very least be of general interest. For example, if the library versions of e1071 and ape are specified for a specific stylo release like 0.7.5, then in the future all you'd need to do is to checkout the relevant tag or commit to have the program work as it always did — bugs included of course, but that'd be intentional.