Disallow uploads when free disk space falls below minimum configured
minimum free disk space.

This fixes issue #535

- New keys in [BBS] section of sbbs.ini:
  MaxLoginInactivity (default: 10 minutes)
  MaxNewUserInactivity (default: 60 minutes)
  MaxSessionInactivity (default: none/unlimited)
- Each configured external program/door in SCFG can have its own maximum inactivity setting (or else the session max inactivity is applied)
- moved node-specific sec_hangup to system-wide/shared max_getkey_inactivity (configured in SCFG->System->Advanced)
- moved node-specific sec_warn (seconds of inactivity before sending warning) to inactivity_warn (a percentage of elapsed max inactivity before sending warning), also configured in SCFG->System->Advanced and used for both socket and getkey inactivity detection
- Renamed JS console.inactivity_hangup to console.max_getkey_inactivity (old name remains as alias)
- Renamed JS console.timeout to console.last_getkey_activity (old name remains as alias)
- Removed JS console.inactivity_warning
- Added JS console.max_socket_inactivity (current input_thread inactivity threshold)
- New text.dat string: InactivityAlert (just contains 3 ^G/BELLs by default) used for non-visual inactive-user warning

The MaxLoginInactivity setting in particular solves the problem of custom scripts (e.g. animated pause prompts) that just poll indefinitely for user input and never time-out  - these will no longer cause nodes to be tied-up with inactive/bot users at login.

You may ask yourself, how did I get here? No, you may ask yourself: why configure these socket inactivity max values in sbbs.ini? The reason is consistency: sbbs.ini is where the MaxInactivity is configured for all the other TCP servers and services.

This fixes issue #534 for Krueger in #synchronet

Instead of copy/pasta. No change in function,.

... to make property names more consistent (e.g. with bbs.last_node).
The old names (without the underscores) are still usable but won't appear
in JSDOCS (i.e. jsobjs.html).

This allows scripts (e.g. login.js) to have custom behavior (e.g. shortening
the maximum inactivity timeout) based on how close the current node is to the
configured last node number. There may be other uses too, but for the vast
majority of Synchronet systems, first_node will always be 1 and last_node the
same as system.nodes/lastnode. Ugh, inconsistent naming. :-(

Add some missing descriptions, fix the order of others.

Mainly capitalization, but some typos and added details. 

number rmfiles(directory, spec=*, keep=0)

Removes files and sub-directories, recursively. Use with caution!

sbbs_t::pause() and JS console.pause()...
now excepts an optional set_abort argument (default is true) which controls whether this method will set the global console-output aborted flag (sys_status&SS_ABORT in C++, console.aborted in JS) when the user hits the Quit or No key at the pause prompt.

This method now returns a bool: false if the user entered No, Quit, or Ctrl-C  at the pause prompt.

Nothing makes use of either of these new pause() features yet, but its generally better to not set/rely on global state wherever possible.

For archives with directories, the first call to extract_files_from_archive() from extract_diz() would create sub-directories in the target (temp) directory, but no files within them.

To correctly solve the original problem identified in commit 79a302f4, introduce/use a new 'recurse' argument to extract_files_from_archive() which means to recursively apply the file_list filter (if specified). Always pass 'with_path' argument as false to prevent sub-dir creation.

The JS Archive.extract() method now excepts an additional boolean argument (recurse) following the file list arguments, default is false.

Remove extra whitespace in Archive JSDOC method descriptions to be consistent with other object/class docs.

The connected TCP port detection method only worked for IPv4, so automatically
detecting a CBM/PETSCII connection over IPv6 didn't work. Thanks to Deuce's
xp_sockaddr and helper functions, this was an easy change.

service_client->client is NULL in these failure/error cases, so get the
protocol string from the service_client->service (which is not NULL) instead.

It's possible that some values (e.g. "16384P") exceed the storage (count of
bytes) of a 64-bit integer, and such values were causing floating point
exceptions when running sbbsctrl.exe, e.g.
Faulting application name: sbbsctrl.exe, version: 3.20.0.0, time stamp:
0x00000000
Faulting module name: gdi32full.dll, version: 10.0.19041.2604, time stamp:
0x2b5302d5
Exception code: 0xc0000090

but interesting (and perhaps a clue), not with sbbs.exe.

Anyway, this added range checking, limiting the maximum value to INT64_MAX
(after division by unit, though there was no division-unit in the problem
case, the "min_dspace" value parsing in scfglib2.c). Using conditional/ternary
return statement had the same floating point exception occurrences, so this
if-statement shouldn't be removed/changed/optimized!

I suspect this has something to do with mix of Borland and MSVC run-time libs
and perhaps different expectations or setups with regards to floating point
exceptions. I did notice that when stepping through read_file_cfg(), I would
get different return values for the same call to iniGetBytes() depending on
whether it was initiated from sbbsctrl.exe (built with C++Builder) or
sbbs.dll (built with MSVC).

Thanks to Codefenix for providing the sample file.ini file that demonstrated
the issue. This problem would've been very hard to root-cause otherwise!

Previously, there was no good way for the caller to determine if the\
user opted (when prompted) to actually log-off or not.

No change in behavior.
Eventually would like to get rid of all the CRLF (and CLS) macro usage.

That's all these macros were doing anyway, so no change.

Does exactly the same thing, no change in behavior and unlikely there's any change in performance.

But... as rightful member of sbbs_t, thus useful from other scopes.

Should get rid of all use of SYNC/ASYNC now then.

Before now, if the sysop enabled login-by-user-number and the specified login
ID *started* with a decimal digit, it'd be treated as a user number and
converted to a 32-bit integer. This could result in weird stuff, like this
error I got today:
SMTP ... !ERROR -2 getting data on user (7000401005.gc7gg@synchro.net)

7,000,401,005 is clearly greater than the number of users in my user base
on Vert, but since 7B is > 2.1B (0x7fffffff), the number would be parsed as
a *negative* integer value and thus less than the total number of users in my
userbase.

An obvious solution would be to just turn of login-by-user-number, and for
most systems, I suggest doing that (a system is less secure with it enabled).

However, I want to leave the option for sysops (at least for now) and don't
want this weird behavior so, a login by user number now requires that the
entire login ID is just decimal numbers, nothing else, and the number is
parsed as an unsigned integer. So yes, roll-over can happen for very high
numbers (>4.2B), but in no instance will the number be parsed as negative and
thus lead to an invalid user record look-up attempt.

Previously, there was no real way to tell if the call to telnet_gate() or rlogin_gate() was successful (e.g. to display or an error message to the user), though there were error/warning messages logged for the sysop. Equivalent JS bbs object methods now return Boolean too.

Include ":port" part of address argument to bbs.[telnet|rlogin]_gate methods in JSDOCS.

Removed a bunch of extraneous (copy-pasted?) JS_SET_RVAL() calls from js_bbs.cpp. This just makes the code a little easier to grok.

1) In the BBS list, show flow control, not TCP port
2) Properly ignore DCD

These methods aren't normally needed (msg scan config/ptrs are
automatically loaded upon logon and saved upon logoff), but for users
(e.g. sysops) that can be logged-in concurrently or experimenting with
scans, these methods can be useful and I plan to expose in a loadable
module next.

Clarify the JS bbs.reinit_msg_ptrs() method description a bit.

This fixes issue #62

Right now, the only preference is reverse mail listings (oldest first
or newest first). These settings are only used when reading "your mail",
not any other kind of mail reading.

bbs.read_mail() now returns the user-adjusted loadmail_mode value and
this allows us to determine the user's preferences and save them after
this function/method is called. A readmail_mod can now return a number
(other than 0) and that will be used as the return value of this method.

sbbs_t::readmail() now does the adjustment of the passed lm_mode before
calling any installed readmail_mod, so if for example, deleted message
viewing is enabled by the sysop, those LM_* flags might be set now in
the argument to the readmail_mod, wherase they never would before.

There is not yet any way for the sysop to set a new user's default
mail_settings, they'll just default to 0 for now.

email_sec.js will get some adjustments to use/store the
user.mail_settings next.

Handles integer overflow in the summing of user's credits and remaining daily
free credits.

Caught by a GCC warning.