Seamless R and C++ Integration with Rcpp (Use R!)

@F.Privé: I prefer [primary sources such as the Rcpp book](https://www.amazon.com/Seamless-Integration-Rcpp-Dirk-Eddelbuettel/dp/1461468671/ref=as_sl_pc_qf_sp_asin_til?tag=rcpp-20&linkCode=w00&linkId=3T5SIL7YILBM32PB&creativeASIN=1461468671).