Work around bogus 7c.b5 blocks in some messages that have been read. They appear to have attachments, but of some unknown format. Before the message was read, it did not have any attachments. Use autoscan to cleanup our autoconf system. Use autoconf to detect when we need to use our XGetopt files and other header files. More fields, including BCC. Fix missing LE32_CPU byte swapping for FILETIME types.

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