DOCS: testing usage of roxygen2 for documentation.

[dalloliogm]

This is an alternative approach to creating documentation.

To generate documentation: load devtools, then run document() from the main folder of the package.

This will automatically generate man pages from the documentation in roxygen2 format (http://kbroman.org/pkg_primer/pages/docs.html)

The generated man page may not work properly yet, probably because of conflicts with manually generated man pages

Refers to #41

[dalloliogm]

closed as I am renaming the branch