new_CppObject_xp .. constructor in 2.16; and how to configure TravisCI

[bgoodri]

In tools/make_cpp.R, you need to change line 36 from

constructors = list(c("SEXP", "SEXP")), fields = character(),

to

constructors = list(c("SEXP", "SEXP", "SEXP")), fields = character(),