vchoi_fork

[svn-r4717] 
Purpose:
     a bug fix
     a feature added
Description:
    1.conversion of unlimited dimension data with the current dimensional size 0
    2. Use a parameter file to control some special cases:
        1) To subdivide the huge array into hyperslabs, a memory buffer size has i
           to be set.
        2) when current dimensional size is 0, a default chunk size can be set.
Solution:
bug fixed    1. Old approach: the current dimensional size is set to H5S_UNLIMITED, which is
                  a huge number. The default chunk size is set as a *FIXED* default value.
    2. New approach: the current dimensional size is set to the current value 0.
                     Users can provide the chunk size through a parameter file.

Platforms tested:
    eirene
    [machines you have tested the changed version.  This is absolute
    important.  Test it out on at least two or three different platforms
    such as Big-endian-32bit (SUN/IRIX), little-endian-32(LINUX) and
    64-bit (IRIX64/UNICOS/DEC-ALPHA) would be good.]