Log Message:
Update to 0.12.6

Upstream changes:
Changes in Rcpp version 0.12.6 (2016-07-18)

    Changes in Rcpp API:

        The long long data type is used only if it is available, to avoid \ 
compiler warnings (Kirill Müller in #488).

        The compiler is made aware that stop() never returns, to improve code \ 
path analysis (Kirill Müller in #487 addressing issue #486).

        String replacement was corrected (Qiang in #479 following mailing list \ 
bug report by Masaki Tsuda)

        Allow for UTF-8 encoding in error messages via \ 
RCPP_USING_UTF8_ERROR_STRING macro (Qin Wenfeng in #493)

        The R function Rf_warningcall is now provided as well (as usual without \ 
leading Rf_) (#497 fixing #495)

    Changes in Rcpp Sugar:

        Const-ness of min and max functions has been corrected. (Dan Dillon in \ 
PR #478 fixing issue #477).

        Ambiguities for matrix/vector and scalar operations have been fixed (Dan \ 
Dillon in PR #476 fixing issue #475).

        New algorithm header using iterator-based approach for vectorized \ 
functions (Dan in PR #481 revisiting PR #428 and addressing issue #426, with \ 
futher work by Kirill in PR #488 and Nathan in #503 fixing issue #502).

        The na_omit() function is now faster for vectors without NA values \ 
(Artem Klevtsov in PR #492)

    Changes in Rcpp Attributes:

        Add cacheDir argument to sourceCpp() to enable caching of shared \ 
libraries across R sessions (JJ in #504).

        Code generation now deals correctly which packages containing a dot in \ 
their name (Qiang in #501 fixing #500).

    Changes in Rcpp Documentation:

        A section on default parameters was added to the Rcpp FAQ vignette \ 
(James Balamuta in #505 fixing #418).

        The Rcpp-attributes vignette is now mentioned more prominently in \ 
question one of the Rcpp FAQ vignette.

        The Rcpp Quick Reference vignette received a facelift with new sections \ 
on Rcpp attributes and plugins begin added. (James Balamuta in #509 fixing \ 
#484).

        The bib file was updated with respect to the recent JSS publication for \ 
RProtoBuf.