Fix CRAN Citation (#8)

* Redocument

* Build with new Rcpp version

* Fix citation issue close #7

* Increase requirements

* Update news

* Bump cran comments

* Fix URLs

* Remove README doi...

Roll CRAN release 1.3.1 (#6)

* Re-generate documentation...

* Change order...

* Avoid building vignettes...

* Bump news [skip-ci]

* Missed the build args...

* Fix spelling errors

Bugfix: Remove Bitwise Shift and use Xi (#2)

* 1. Switch from using a bitwise shift to using the correct comparison
2. Use the subset variant of X for the subject.

* Ensure cIRT is exported.

* Code formatting in the vignette

* Restrict text to 80 characters in vignette.

* Add a bullet point to NEWS.md

* CITATION spacing [skip-ci]