NNTP/pdcurses now working on Windows [2nd try]

[1st try was rejected for oversize image attachment]

Hi Team,

I probably have some more testing to do to verify that I haven't
broken anything, but with boost.asio and pdcurses, I have a native
Win32 version working in cmd.exe.  See attached screen shot.

Screen shot here:
<https://user.xmission.com/~legalize/trn/trn-basic-win32.png>

Not bad :).  I even have a way to test basic NNTP conversation between
trn and a mocked server.  With what I recently learned about SSL/TLS and
boost.asio I should be able to add nntps and STARTTLS support to trn
without much difficulty.

I added some more unit testing around my nntp changes and found a few
little bugs that I fixed.  The NNTP style used by trn is quite old,
using non-standard extensions for facilities that are now covered by
extensions.  It doesn't use the CAPABILITIES command at all to
identify extensions it could use.

INN (what almost everyone uses for NNTP servers these days) is very
forgiving, so these things don't result in failures, but trn should be
more properly using the CAPABILITIES command and commands that have
been standardized to replace the ad-hoc extension commands.

The curses usage on Win32 might be a little goofy; some things are
hardcoded that should probably be queried from pdcurses.

Now that I have basic NNTP on Windows, I think it's time to revisit
the Linux side of things and make sure everything is working there.
I'm going to first try with WSL since that is the most accessible to
me at the moment.

Cheers,

-- Richard

-- 
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