hdf5_ep

[svn-r3412] Purpose:
    Code cleanup
Description:
    Cleaned the code up a bit getting rid of some warnings about "const"
    being lost from passing a const char * to a function, etc.

    Also force the error messages to stderr instead of simply printing
    them to stdout. The same behaviour can be achieved by running h5dump
    like:

            h5dump ... 2>&1

    however, the error reporting before this change wasn't consistent in
    its use. I also made some of the error messages clearer (giving names
    of the failed types and, when there's an "internal error", reporting
    the line number the error occurred on so that we can debug).
Solution:
    Converted to "fflush(stdout); fprintf(stderr,...);" for all error
    reportings.
Platforms tested:
    Linux