Improved support from removing rows in crud tabs.

It can handle now complex selections and reports back errors encountered
when removing the rows fails.

pgsql/Pgsql_Connection.h

@@ -114,6 +114,7 @@ namespace Pgsql {
 		PGconn *conn = nullptr;
 		std::function<void(const PGresult *)> notifyReceiver;
 
+		void throwError(PGresult *result) const;
 		static void notifyReceiveFunc(void *arg, const PGresult *result);
 	};