New error messages

Test of unsigned BIGINT values
Fixes for queries-per-hour
Cleanup of replication code (comments and portability fixes)
Make most of the binary log code 4G clean
Changed syntax for GRANT ... QUERIES PER HOUR

sql/sql_class.h

@@ -370,7 +370,7 @@ public:
   */
   ulong	     slave_proxy_id;
   NET*       slave_net;			// network connection from slave -> m.
-  uint32 log_pos;
+  my_off_t   log_pos;
 
   THD();
   ~THD();