vchoi_fork

[svn-r29269] Purpose: Improve Packet Table library
Description:
    The Packet Table API used to have fixed-length and variable-length functions
    (i.e., H5PTcreate_fl and H5PTcreate_vl), but in 2006, the vlen functions
    were ifdef'ed out with VLPT_REMOVED, see HDFFV-442. The majority of this
    revision includes removing unused vlen stuff, adding various vlen tests,
    initial code cleanup, and first pass of commenting.
    Details:
      - Removed the VLPT_REMOVED ifdef, but keep H5PTis_varlen and the free
        function because they are useful or even needed, but the free
        function's name is changed to be more appropriate for both
        read/write buffers, i.e., H5PTfree_vlen_buff.

      - The new test file, test_packet_vlen.c, contains tests showing packet
        tables, containing various types of vlen data, can be created with
        the fixed-length function

      - Two accessor functions were added per HDFFV-8623/patch 003.
            /* Returns the ID of the dataset associated with the packet table */
            hid_t H5PTget_dataset(hid_t table_id);

            /* Returns the ID of the datatype the packet table uses */
            hid_t H5PTget_type(hid_t table_id);

      - Various cleanup: replacing 0/-1 with SUCCEED/FAIL and H5I_BADID with
        H5I_INVALID_HID, and removing many warnings.

Platforms tested:
    Linux/32 2.6 (jam)
    Linux/64 (platypus)
    Darwin (osx1010test)