hdf5_msb

[svn-r13292] Description:
    Add feature to h5copy to allow it to add an object to an existing file,
instead of blowing away existing file.

    Modify h5tools_fopen() routine to take access flags, so it can be used
to open an existing file for writing.

    Added check to h5copy test script that verifies it has produced a file
with the correct structure.

Tested on:
    Linux/32 2.6 (chicago)
    Linux/64 2.6 (chicago2)