Branch: b_new_cmd

Branch: b_new_cmd
1 add mti_transno_flag to check whether this req handler need transno update
  for those lnk and some special node. we do not need.
2. set DISP_OPEN_OPEN in correct place
3. do not do unlink log in mdd_unlink. since it should only unlink the
   metaobject. add the unlink log after open orphan is implemented.