hdf5_ep

[svn-r25204] Description:
    Set OUTPUT_DIRECTORY to cpplus_RM and HTML_OUTPUT to '.' because
    they were reset by accident causing "bin/release doc" to fail.

    Ran bin/release to verify the failure was gone.
    Merged from trunk: r25202

    Also, removed from functions' comments some arguments that are only
    applicable to the trunk.  Doxygen gave warnings.

Platforms tested:
    Linux/32 2.6 (jam) - very minor, only comments