Rcpp 0.11.4

As usual, see

• https://github.com/RcppCore/Rcpp/blob/master/inst/NEWS.Rd
• https://github.com/RcppCore/Rcpp/blob/master/ChangeLog
• http://dirk.eddelbuettel.com/blog/2015/01/24#rcpp_0.11.4

for more details, and use the CRAN package with the R package management tools for installation.