hdf5_ep

[svn-r6390] Purpose:
    Update

Description:
    Removed some obsolete fields - such as the AC_subst_t object ID -
    which isn't needed. Fixed so that there are fewer global variables.
    There are still some left, however. Modified the client and server
    code so that it handles read requests better. There were some flaws
    in how this was done before (it was calling H5FD_read() instead of
    just returning the status that it couldn't find the metadata in the
    cache).

Platforms tested:
    Linux