implemented in the client library and server.
Warning: this makes the new client library and server incompatible with all 
previous versions and 5.0.


libmysql/libmysql.c:
  Make client library compatible with future extensions: types of placeholders, 
   names of named parameters, cursors and array execution.
sql/sql_prepare.cc:
  Alpha server side support for future extensions: types of placeholders and names of
  named parameters are sent to client (virtually), cursor flags and execution
  count received in COM_EXECUTE packet are ignored.