Switch to arma_cerr_stream<T>

[eddelbuettel]

Armadillo updates its coding convention over time. We have been fairly hard at work to have RcppArmadillo-using packages switch from a now-deprecated older way of instantiatig variables to a newer one (see issue #391 for details; this PR is part of the related issue #402).

When compiling packages using RcppArmadillo with the deprecation-warning-suppressor we still use, some new warnings come up. One concerns a deprecated way of setting an output or error stream as your package does in one spot in one file. Changing this is fairly straightforward, and affects only that one file.

The package compiles with the change as it did before, and test fine as well.

It would be much appreciated if you could apply this pull request and update the package at CRAN within the next few months. Let me know if you have any questions.

[bstewart]

Thanks so much for taking the time to do this @eddelbuettel and for all your contributions to the R community. I'll get this tested and pulled in soon and pushed to CRAN in the appropriate timeframe.

[eddelbuettel]

Thanks for the very prompt reply!

[conradsnicta]

@bstewart A better solution is to simply remove all use of arma::set_cerr_stream(). No replacement code should be necessary.

Armadillo by default prints far fewer warnings since version 10.4, so use of arma::set_cerr_stream() is not required.

More details at: RcppCore/RcppArmadillo#402 (comment)