Need testing on big-endian machines. We may be missing some LEnn_CPU()
calls.

pst2diii needs header and mime type updates from readpst.

At the next soname bump (to libpst.so.5) we should
    move some of readpst into the shared library, in particular write_normal_email()
    remove readpstlog, and produce ascii debug log files
    add debug FILE* into the pst_file structure, so all debug printing
        will be passed the pst_file struct. Also add a semaphore in there
        to synchronize debug printing.