1. Fixes within the testscripts   (affects rpl_ddl.test and rpl_ndb_ddl.test)
   - slave connection is only an observer (-> AUTOCOMMIT = 0)
     This removes the problem with the hanging test around DROP DATABASE (NDB). The hanging test around DROP DATABASE is a difference to InnoDB/MyISAm behaviour but fare
     away of a clear bug. IMHO this behaviour does not violate the SQL standard and should be therefore simply accepted.   
   - removal of wrong comments
   - CREATE/DROP TEMPORARY TABLE must not cause implicit commit of the current transaction.
     NDB behaves here correct and InnoDB/Falcon wrong.
   - Add a missing connection slave
   - Reenable the test rpl_ndb_ddl.
2. Disable rpl_ddl.test because of Bug#26418.
3. Reenable rpl_ndb_ddl.test
4. Improvements (affect rpl_ddl.test and rpl_ndb_ddl.test)
   - Better + extended comments which should prevent that somebody accidently destroys the logics of the test
   - Replace SELECT's printing comments by "--echo"  (decreases the number of auxiliary SQL commands)
   - Remove the need for include/rpl_stmt_seq2.inc   (was mostly redundant to rpl_stmt_seq.inc)
   - Remove extra/rpl_tests/rpl_ndb_ddl.test         (corrected extra/rpl_tests/rpl_ddl.test is sufficient)  
   - Shift assignment of values to $show_binlog, $manipulate (variables useful for debugging) into the toplevel scripts
   - The temporary tables get now their storage engine from the variable $temp_engine_type. (more deterministic testing conditions)
   - Add additional protocol line if the connection is switched (was partially missing)
   - Add two DML commands for comparison purposes