A little more visiblity into the MQTT library (version, function return values)

Recently started truncating trailing whitespace from sender/recipient names
before calculating the CRC value (similar to what we do for message subjects
as of a year ago). To suppress errors when evaluating messages (with trailing
whitespace in sender or recipient namems) created or imported before this
change, use this new -N option.

Make it obvious when a message header value string has trailing white-space.
Make this function (and binstr()) thread-safe by eliminating the local static
variable.

This should prevent programs using rgbmap (ie: SyncTERM) from
having an exectuable stack on Linux.

And don't offset long(er) windows from edges to allow more options to be
on screen at once.

Tested with 50 column mode.

Maximize screen realestate for options/settings display:
- Don't place a margin around windows when in a narrow screen mode.
- Don't display shadows on windows when in a narrow screen mode.

This commit also fixes a bug in uinput() when left was non-zero and the total
width (left + width) would be too wide for the screen. This bug was apparent in
SCFG->Message Areas in 50 column mode (no Message Group window would be
displayed when a message group was selected).

Some BBS packages tack on trailing whitespace on names, e.g.
https://github.com/wwivbbs/wwiv/issues/1607

Fixes Windows build.

Right now, only supports publish, subscribe to come next.

Only included with the mosquitto lib support is enabled in the build.

Only on Linux, Documented as VSWTCH (also added), as a SysV-only
thing but actually defined a VSWTC, must be disabled (ie: set to
_POSIX_DISABLE) to not show up in stty as being modified.

*sigh*

I'm not convinced Linux developers want termios to work.

Be sure to set them first though, since they may overlay with
other ICANON entries.

The wrong characters in the wrong order.  I have no idea why they
even have the thing defined, but we'll just stop using it since
it seems BSD systems are the only ones where it's useful...
instead just set V* to C* except ERASE and ERASE2 which we set both
to CTRL-H

The the date/time display would overwrite parts of the application
title in narrower screen modes, so let's not do that.

No functional change, just a little clean-up.

ftouch(), semfile_signal(), and JS file_utime() would fail to update a file's access/mod times with errno=EPERM if not run as the file's owner. From "man utime":

EPERM times is not NULL, the caller's effective UID does not match the owner of the file, and the caller is not privileged (Linux: does not have the CAP_FOWNER capability).

So use a NULL times parameter value when updating to a file's time stamp(s) to the current time.

- getscaling() incorrectly used an int intermediate variable
  This would force scaling to an integer value when read.
- Only parse ConfigureNotify events describing a change to the SyncTERM window
  It appears that XWayland on ChromeOS was occasionally sending a
  ConfigureNotify event describing some other window to SyncTERM,
  and that window had a 1x1 size, which would cause SyncTERM to
  assert minimum size again (usually 640x480), which would set
  scaling to 1.0.

One of the benefits of the new .ini format config files. :-)

This increase introduced a few potential buffer overrun warnings (all writes
to smb_t.file ?)

... using snprintf() instead of sprintf()

Since we are now free()ing the opt[] items in bail(), I've seen heap
corruption core dumps after navigating the SCFG menus with some long
configuration items (e.g. timed events with max-length command-lines).
This heap corruption has been present for a long, long time, but not
detected since we weren't free()ing these heap-allocated items.
Increasing MAX_OPLN would have been a mitigation for this issue, but
using snprintf(opt[n],MAX_OPLN,...) is the better fix.

The -strip option requires the (new to v3.20) strip_ctrl_a() method

Previously, when using the -all or -lib options, all directories would be
included in the filelist, but with the -user option, a valid user (e.g.
-user=guest, or -user=sysop) can be specfied to limit the scope of the list
to only directories accessible to the specified user (and downloads allowed
to the user as well).

The -utf8 option encodes all output in UTF-8 (instead of CP437) while the
-strip option strips any Ctrl-A (attribute) sequences from the output.

Copy/pasted (with little modification) from
https://synchro.net/docs/file_section.html#AdvancedOptions -> "Short Name:"

Some short names have specially predefined meaning and it's important to
include that detail here.

Unlike strip_ctrl(), does not remove any other control characters from string.

1) In savescreen(), if the vmode is not found, explicitly set
   pixels to NULL rather than leaving it uninitialized.
2) Ensure that currmode is never left as _ORIGMODE (which is not
   a defined mode, so can result in vmode not being found).

Caught/fixed by Deuce in Brookville, OH