hdf5_ep

[svn-r11712] Purpose:
    New feature

Description:
    Check in baseline for compact group revisions, which radically revises the
source code for managing groups and object headers.

WARNING!!!!  WARNING!!!!  WARNING!!!!  WARNING!!!!  WARNING!!!!  WARNING!!!!
WARNING!!!!  WARNING!!!!  WARNING!!!!  WARNING!!!!  WARNING!!!!  WARNING!!!!

    This initiates the "unstable" phase of the 1.7.x branch, leading up
to the 1.8.0 release.  Please test this code, but do _NOT_ keep files created
with it - the format will change again before the release and you will not
be able to read your old files!!!

WARNING!!!!  WARNING!!!!  WARNING!!!!  WARNING!!!!  WARNING!!!!  WARNING!!!!
WARNING!!!!  WARNING!!!!  WARNING!!!!  WARNING!!!!  WARNING!!!!  WARNING!!!!


Solution:
    There's too many changes to really describe them all, but some of them
include:
    - Stop abusing the H5G_entry_t structure and split it into two separate
        structures for non-symbol table node use within the library: H5O_loc_t
        for object locations in a file and H5G_name_t to store the path to
        an opened object.  H5G_entry_t is now only used for storing symbol
        table entries on disk.

    - Retire H5G_namei() in favor of a more general mechanism for traversing
        group paths and issuing callbacks on objects located.  This gets us out
        of the business of hacking H5G_namei() for new features, generally.

    - Revised H5O* routines to take a H5O_loc_t instead of H5G_entry_t

    - Lots more...

Platforms tested:
    h5committested and maybe another dozen configurations.... :-)