Recover current view from state after SST.

When member joins the group and needs to receive an SST it won't
receive the corresponding menbership view event because the SST
happens after the event and will already include the effects of
all events ordered before it. The view then must be recovered from
the received state.

Minor renames and cleanups.

References codership/wsrep-lib#18

include/wsrep/server_service.hpp

@@ -130,6 +130,17 @@ namespace wsrep
             wsrep::high_priority_service* high_priority_service,
             const wsrep::view& view) = 0;
 
+        /**
+         * Recover a cluster view change event.
+         * The method takes own node ID.
+         *
+         * @param client_service Reference to client_service
+         * @param own_id this node ID obtained on connection to cluster
+         */
+        virtual wsrep::view get_view(
+            wsrep::client_service& client_service,
+            const wsrep::id& own_id) = 0;
+
         /**
          * Log a state change event.
          *