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/man/xgb.model.dt.tree.Rd

@@ -1,4 +1,4 @@
-% Generated by roxygen2 (4.1.1): do not edit by hand
+% Generated by roxygen2: do not edit by hand
 % Please edit documentation in R/xgb.model.dt.tree.R
 \name{xgb.model.dt.tree}
 \alias{xgb.model.dt.tree}
@@ -45,15 +45,16 @@ The content of the \code{data.table} is organised that way:
 \examples{
 data(agaricus.train, package='xgboost')
 
-#Both dataset are list with two items, a sparse matrix and labels
-#(labels = outcome column which will be learned).
+#Both dataset are list with two items, a sparse matrix and labels 
+#(labels = outcome column which will be learned). 
 #Each column of the sparse Matrix is a feature in one hot encoding format.
 train <- agaricus.train
 
-bst <- xgboost(data = train$data, label = train$label, max.depth = 2,
+bst <- xgboost(data = train$data, label = train$label, max.depth = 2, 
                eta = 1, nthread = 2, nround = 2,objective = "binary:logistic")
 
 #agaricus.test$data@Dimnames[[2]] represents the column names of the sparse matrix.
 xgb.model.dt.tree(agaricus.train$data@Dimnames[[2]], model = bst)
+
 }