hdf5_ep

[svn-r6753] Purpose:
Code cleanup

Description:
Replaced the comm/info freeing with H5FD_mpio_comm_info_free to make
it cleaner and consistent.
Replaced couple FUNC_LEAVE_NOAPI(SUCCEED) with FUNC_LEAVE_NOAPI(ret_value).
These were bugs since it was possible errors may occur at FUNC_ENTER...()
time and this hardcoding would not report those errors.
Documented some modification history.


Platforms tested:
Did not h5committested because these are all MPI code and well protected
by HAVE_PARALLEL.
Tested in eirene and modi4, both parallel mode.

Misc. update: