Support for sending serial breaks, in both the Windows and Unix
serial backends.

[originally from svn r6832]
The Windows HANDLE type, despite being a `void *', does not actually
behave like a pointer. In particular, the right thing to set a
HANDLE to to indicate that it's invalid is INVALID_HANDLE_VALUE, not
NULL. Crack down on sloppy use of NULL HANDLEs across all Windows
code.

(There is one oddity, which is that {Create,Open}FileMapping are
documented to return a NULL HANDLE instead of INVALID_HANDLE_VALUE
on failure. Shrug. If MS want to be inconsistent, I suppose I have
to live with it.)

[originally from svn r6833]
Explicitly closing logctx on various kinds of error exit means that
the log file gets fclosed properly and the critical last few
messages might be recoverable from the log file more often...

[originally from svn r6834]
New logging mode, which records the exact bytes sent over the wire
in an SSH connection _in addition_ to the decrypted packets. This
will hopefully come in useful for debugging wire data corruption
issues: you can strace the server, enable this mode in the client,
and compare the sent and received data.

I'd _like_ to have this mode also log Diffie-Hellman private
exponents, session IDs, encryption and MAC keys, so that the
resulting log file could be used to independently verify the
correctness of all cryptographic operations performed by PuTTY.
However, I haven't been able to convince myself that the security
implications are acceptable. (It doesn't matter that this
information would permit an attacker to decrypt the session, because
the _already_ decrypted session is stored alongside it in the log
file. And I'm not planning, under any circumstances, to log users'
private keys. But gaining access to the log file while the session
was still running would permit an attacker to _hijack_ the session,
and that's the iffy bit.)

[originally from svn r6835]
Updates for today's changes:
 - changes to Logging panel
 - breaks in serial backend
(Plus, completely unrelated, an index term entry related to port forwarding
which seems to have been sitting around for ages, possibly waiting for me to
think about `see also' index terms in Halibut.)

[originally from svn r6836]
Add a mini-rant to the top comment explaining why threads are
required. (I just tried getting rid of them; it worked fine for
serial ports, but not for anything else. The Windows I/O API sucks.)

[originally from svn r6843]
Support for an alternative mechanism for displaying wide characters
under X: instead of having two separate fixed-width fonts one of
which is twice the width of the other, you can instead have a single
font in which some characters are twice as wide as others.

This is implemented very simply: if you specify a wide font, it will
be used for wide characters, and if you don't then the normal font
will be used for wide characters (so they'd better _be_ wide in that
font, or there'll be trouble).

I got this idea from Jed, whose latest version supports UTF-8 and
requires a font of this type. If there are going to be X fonts like
that kicking around, there will doubtless be people who want to use
them.

[originally from svn r6844]
Slight change to password expiry UI for the benefit of Cisco servers, which
are as usual slightly odd.

[originally from svn r6845]
I seem to have slightly funted Plink's display of banners etc in r6437, oops.
Fixed.

[originally from svn r6846]
[r6437 == 8719f92c1426609de7ead4a490a15d1d18875f53]
CSI 3 J now clears the scrollback, as in xterm.

[originally from svn r6847]
[this svn revision also touched putty-wishlist]
Note that the dynamic-tunnel proxy does not support UDP, since we get asked
about this quite often.

[originally from svn r6855]
Fix breakage of `Restart Session' in r6802. When restarting the
session, we were clearing the new session_closed flag, but failing
to clear must_close_session; with that set, the session was being
opened but immediately re-closed.

[originally from svn r6857]
[r6802 == 0dcdb6c3c19ecae20dcc6f947169b3c98bcbae9d]
IXON and IXOFF belong in _iflag_, not cflag! While I'm here, be more
reliable in clearing of RTS/CTS flags.

[originally from svn r6864]
Disable a bunch of undesirable termios flags. ICRNL, in particular,
is liable to have been set on serial ports previously used as
terminal devices, and definitely wants not to be set on serial ports
being used for callout.

[originally from svn r6865]
Minor semantic tweak to bug-compatibility modes: make
BUG_NEEDS_SSH1_PLAIN_PASSWORD do exactly what it says on the tin, independent
of whether BUG_CHOKES_ON_SSH1_IGNORE is set.

This is invisible in the default configuration, as all servers marked as having
the second bug have the first one too, but it would allow one to manually
configure PuTTY to cope with a SSH-1 server that got upset by ignore messages
during authentication, but was fine with their use as keepalives.

[originally from svn r6876]
Spotted by Tim Kosse: we were returning an incorrect path in canonify() when
we couldn't get any sense out of the server.

[originally from svn r6877]
Tiny comment fix.

[originally from svn r6885]
Administrivia: most SSH-2 specs are no longer drafts.

[originally from svn r6890]
There's been an increase in people posting non-SSH PuTTY-related questions
to comp.security.ssh, posting queries that are clearly about PuTTY to
newsgroups without actually mentioning PuTTY, and so on. They may have been
directed there by this document :( Add a futile attempt to instil a sense of
etiquette.

[originally from svn r6895]
Link to faq-cleanup from faq-settings.

[originally from svn r6904]