hdf5doc

Description:
    H5Gcreate_expand, H5Gcreate --
    H5Tcommit_expand, H5Tcommit --
        Update to current syntax (H5*_expand only) and
            explain changes related to use of H5Llink (all 4 functions).  
        Move "create missing groups" example from H5Gcreate_expand to H5Llink.
        Add sections listing differences between:
            H5Gcreate_expand and H5Gcreate in H5Gcreate_expand
            H5Tcommit_expand and H5Tcommit in H5Tcommit_expand
        Edits from technical review.
    H5Dcreate_expand, H5Dcreate -- 
        Update H5Dcreate with regarding the use of H5Llink and
            notes regarding H5Dcreate / H5Dcreate_expand common behaviors.
        Add H5Dcreate_expand,
            with section listing H5Dcreate / H5Dcreate_expand differences.
        Edits from technical review.
Tested:
    Safari, Firefox