add naive topdown and finish refactoring

Author: AngelPone

NAMESPACE

@@ -13,6 +13,7 @@ export(marginal2Joint)
 export(point_forecast)
 export(reconcile)
 export(reconcile_train)
+export(stepwise_reconcile.train)
 export(topdown.train)
 import(Matrix)
 import(dplyr)