Bug fix
Description:
Variable length strings and sequences with NULL pointers were not handled
by library, causing problems access the data. This also affected fill values
for variable-length datatypes.
Solution:
Address the issues in the library by detecting NULL sequences/strings
and avoid trying to convert them.
Patched up dumper to display NULL sequences/strings.
Platforms tested:
FreeBSD 4.9 (sleipnir)
h5committest
