Don't export Progress RC class.

Closes tidyverse#535

NAMESPACE

@@ -292,7 +292,6 @@ S3method(update,tbl_sql)
 export("%.%")
 export("%>%")
 export(.datatable.aware)
-export(Progress)
 export(anti_join)
 export(arrange)
 export(as.tbl)
@@ -378,6 +377,7 @@ export(ntile)
 export(order_by)
 export(partial_eval)
 export(percent_rank)
+export(progress_estimated)
 export(query)
 export(rbind_all)
 export(rbind_list)
@@ -438,7 +438,6 @@ export(ungroup)
 export(union)
 export(with_order)
 exportClasses(MonetDBQuery)
-exportClasses(Progress)
 exportClasses(Query)
 import(assertthat)
 importFrom(Rcpp,Rcpp.plugin.maker)