klutometis/roxygen — pull request #90 by renozao (2012-04-17 16:00:33+00:00)
Title: Add support for tags @cite and @bibliography

Hi,

these commits add support for tags @cite and @bibliography so that references to papers can be added via bibtex entries.
All entries are gathered in the file int/REFERENCES.bib in the package directory.
Computations is cached and warnings are thrown for undefined bibtex entries.
So the user can do the following:

1- declare its bibtex database file in any roxygen chunk (e.g. in the chunk that describes the package):

```R
#' @docType package
#' @bibliography /home/user/articles.bib
NULL
```

2- then reference papers in any other chunk, keys must be separated with spaces, multiple @cite tags are possible:

```R
#' @cite Ref2010 Ref2011
#' @cite Otherref
#'
myfun <- function(...){
# ...
# ...
}
```