replacing dedicated threads for read and write with non-blocking
sockets driven from the main window proc. So far it can do a
round-trip against the relay on win32, and compiles but isn't tested
on wince.
Meaning: both exist in the resource, and at runtime we disable the
unwanted one and lookup IDs and sometimes window messages in order to
operate on 'em. Also, spinners send WM_NOTIFY messages, so handle
that. Current implementation is a bit of a hack but works.