* Fix syncing DMatrix columns. * notes for tree method. * Enable feature validation for all interfaces except for jvm. * Better tests for boosting from predictions. * Disable validation on JVM.
* Remove nthread, seed, silent. Add tree_method, gpu_id, num_parallel_tree. Fix #4909. * Check data shape. Fix #4896. * Check element of eval_set is tuple. Fix #4875 * Add doc for random_state with hogwild. Fixes #4919