Description:
    - Added a null terminator to the comment returned from the C call, in
        getComment methods
    - Some minor cleanup
Platforms tested:
    Linux/ppc64 (ostrich)
    Linux/32 2.6 (jam)
    Linux/64 2.6 (platypus)/PGI compilers



git-svn-id: https://svn.hdfgroup.uiuc.edu/hdf5/trunk@24867 dab4d1a6-ed17-0410-a064-d1ae371a2980