Previously, many servers and services didn't support login by real name
(e.g. issue #469) even if the sysop had that option enabled in SCFG.

Move login control settings from node.ini to system (main.ini -> login)

The 3 node toggle options:
- Allow Login by User Number
- Allow Login by Real Name
- Always Prompt for Password

... have been now moved from SCFG->Nodes->Node x->Toggle Options to
SCFG-System->Toggle Options.

If you upgraded to v3.20a before now, you'll want to double-check these
settings to make sure they're how you want them set. New upgraders that run
upgrade_to_v320.js (e.g. via 'jsexec update') will get these settings migrated
automatically.

Added some error detection/logging to upgrade_to_v320.js when failing to open
.cnf files.

Constified some more user/login related function args and return types.

Oversight probably during the new filebase overhaul in v3.19. Reported by Nelgin.

No immediate use, but I thought I had one. I didn't. Still, will probably need these one day.

As apparently these happen a lot when a client disconnects right
away after connecting.

Need to start the MQTT init/thread-start stuff after daemonizing.

Thanks to Nelgin for letting me know this was recently broken.

I'm not sure what purpose this global variable once had, but it wasn't needed
now and it was masking copy/paste issues in some of the sbbs_t methods in this
file. Just make an 'sbbs' local to bbs_thread(), since there's where it's
legit-used.

FYI: All the Cryptlib-SSH macros assume there's an 'sbbs' in scope.

The MSS detection will set this to the best value on a per-connection
basis.  This will allow larger packets to be sent from the BBS.

If something else sets these events, and they never get cleared,
this will fall into a tight loop.

This came about through the realization that the global 'sbbs' in main.cpp
can (and was/is) hiding some copy/pasta bugs.

When the system checks for an incoming byte, if there's any pending
output, send it immediately, bypassing the outbuf highwater mark.

This allows the final non-full packet to be sent without waiting
for the OutbufDrainTimeout (default 10ms), and makes a big difference
when doing a large number of ANSI queries (send an ANSI code, wait
for a response).  There's a small but noticable placebo effect as
well that makes everything feel smoother.

This commit also cleans up the output thread where it pulls from
the ring buffer into the linear buffer to take advantage of the new
event-based ring buffers.  Much easier to read now.

Speaking of easier to read, this also includes some whitespace
fixups.

Seems to work a treat.

We've never really cared how many times the ring buffer has become
empty, how many times data was added to it, or how many times we've
been over the highwater mark.  These have effectively always been
event signalling, with extra hackiness to clear "extra" semaphore
posts.

This commit removes RINGBUF_SEM entirely, and uses events for
everything.  There's an empty event (set when the ring buffer is empty),
a data event (set when the ring buffer is not empty), and a highwater
event (set when the ring buffer has at least highwater mark bytes).

A RingBufWrite() will set data and highwater events if applicable,
and clear the empty event.

A RingBufRead() will set empty event and clear data and highwater
events if applicable.

RingBufReInit() will now set the empty event, and clear the data
and highwater events.

These are the only actions the RingBuf API will perform on the
events, it does *not* clear the highwater event on a RingBufWrite()
if the buffer does not have enough bytes in it for example, this
will *only* be done by RingBufRead() or RingBufReInit().  This
allows consumers to force specific behaviours (such as forcing
the highwater event on shutdown to prevent waiting for it).  Since
the current code was able to deal with the semaphores having
arbitrarily high counts, the existing code shouldn't have any
issue with this.

For things that want to shut something down, we're now setting both
the data and highwater events to ensure it doesn't wait for a
timeout (even for things that don't use highwater like the inbuf).
The RingBuffer API should grow a thing to do this (RingBufferFlush
perhaps?) rather than the consumers poking into the innards
arbitrarily.

Tested on the webserver and RLogin server and seems to be working
great.  sexyz builds.  It seems there's some Windows thing that
uses the ringbuffer sem for something, but I couldn't figure out
what... updated the build file, but no clue if that's broken or not
now... I'm sure DigitalMan will be happy to fix it if CI doesn't
catch it. ;)

This should allow the console object to grow a "flush" method that
will set the highwater and data events.

not scale it in one colour space before translating it to a different
one.

Also, since almost all PPMs will use a maxval of 255, compile that
in as the default so we don't need to generate it.

Update the script to verify pixel operations are supported.

You can copy whole, or portions of a PPM file from the cache directory
to the screen, optionally applying a mask.  The mask can be specified
as a base64-encoded bitmap or as a PBM file in the cache directory.

You can also copy portions of the screen into an internal buffer, and
draw from that internal buffer.  There's plans to support loading an
image file from the cache directory into the buffer as well.

Portions of the buffer can be copied to the screen, optionally
applying a mask as with drawing PPMs.

There's also plans to support copying a PBM file into a mask buffer.

I've added the syncterm-bounce.js script which simply bounces the
SyncTERM icon around the screen like the classic screensaver we all
hate.  I initially wanted to replace the spinning cursor with it,
but there doesn't seem to be a way to replace that with a script. :(

To use the script, just add the text:
@EXEC:syncterm-bounce.js@ to the end of your logon.js script.

Log in to nix.synchro.net with the latest nightly build or build from
git to see the script in action.

the start of wrapped function call continuation lines, but at the
end of struct initializers/enums/etc lines.  I think the least bad
is commas at the end, especially now that it's got the happy
four-space indent for continuations.

I may play with this more later, but this seems to be good for now,
we'll see how it works out in actual use.

I tried a space after too, but that's weird as well and easily
confused with multiplication at first look.

Run uncrustify on this mess.
There's a few small oddities (especially in enums), but this is
much better.

There's no reason to be aggressively ancient.

-b/path/to/bbslist specifies a user BBS list file
-n/path/to/inifile specifies a config file

Remove undocumented -insert option.  This may make nelgin sad, not sure.

... in hopes of debugging issue #468

Also clean up drop files unless -d option is passed.

Incremented version to 0.3.

mqtt_thread_start() actually will fail on Windows currently because we're
using a non-thread-safe version of mosquitto.dll

This moves the mqtt thread start further up before some *nix-specific stuff,
so hopefully that's not an issue.