Update insert_rows() (and _cols()) to two-argument signatures

[eddelbuettel]

When updating RcppArmadillo to no longer suppress deprecation warning, initially for the value setting use described and changed in detail in RcppCore/RcppArmadillo#391, we found one statement in your package also triggering a number of warnings such as

    fastGrplars.cpp:253:38: warning: ‘void arma::Col<eT>::insert_rows(arma::uword, arma::uword, bool) 
       [with eT = double; arma::uword = unsigned int]’ is deprecated [-Wdeprecated-declarations]

This PR addresses them. Armadillo no longers off a variant with a boolean, and seemingly always initializes (so some
of your code comments no longer match).

The package passes its tests as before.

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.

[aalfons]

Thanks so much for providing this fix! I'll submit a new version to CRAN soon.

[eddelbuettel]

Please also see #402 where @conradsnicta commented after I made the series of pull requests. His recommendation and preference is to ... simply remove the setter because even the non-deprecated one I switched is internal, and the suppression should no longer be needed. Apologies for the double-dance.

[eddelbuettel]

Whoops. Please disregard my previous comment. Different issue. For the row/col insertion all is good. Look forward to seeing an updated version at CRAN, and thanks for taking care of it!

[aalfons]

No worries, thanks anyway for reaching out again. I just submitted the new version 0.7.4 to CRAN, it should be available soon.

[eddelbuettel]

And there it is -- thanks again, and thank also for listing me as 'ctb' which is very generous for such a small contribution.

[aalfons]

You've also been kind by already providing a patch instead of just asking to fix it, so thanks again for that!