hdf5doc

Description:
    Added "HDF5 User’s Guide Update Status."
    Added "Additional Resources" with links to "Chunking in HDF5"
        and "Metadata Caching in HDF5." 
    Removed "Special Topics" chapter, moving "Metadata Caching in HDF5" 
        to a new "Advance Topics" collection.
    Updated top-level navigation bar to reflect additions and deletion.
        Removed link to "Using This Guide with HDF5 Release 1.8.x."
    Updated blurb on front page to reflect updates to 1.8 functionality.
Tested:  Firefox