Update lib version dependencies (for DiagrammeR mainly)

Fix @export tag in each R file (for Roxygen 5, otherwise it doesn't work anymore)
Regerate Roxygen doc

R-package/R/xgb.dump.R

@@ -36,7 +36,6 @@
 #' # print the model without saving it to a file
 #' print(xgb.dump(bst))
 #' @export
-#' 
 xgb.dump <- function(model = NULL, fname = NULL, fmap = "", with.stats=FALSE) {
   if (class(model) != "xgb.Booster") {
     stop("model: argument must be type xgb.Booster")