hdf5_ep

[svn-r17239] Purpose: Fix bug and improve readability
Description:
    - Revised DataSet::write to pass in correct string buffer
    - Added member function DataSet::getInMemDataSize() to simplify
      getting the dataset's data size in memory.
    - Added private functions for reading fixed- and variable-len
      string data: p_read_fixed_len and p_read_variable_len.
    - Added tests to write/read array of strings to datasets.

Platforms tested:
    Linux/32 2.6 (jam)
    FreeBSD/64 6.3 (liberty)
    SunOS 5.10 (linew)