Fix GCC warning: field precision specifier ‘.*’ expects argument of type ‘int’, but argument 3 has type ‘long unsigned int’ [-Wformat=]

Parse the attribute flags and print descriptions of the set flags
(except for unused bit-10).
Allow a '-c' option to only print control (kludge) lines from the body text.
The '-b' option displays both body text and control lines (same as before).
Fixed a memory leak and some other bad code examples.
Some minor beautifications.

Lock the mail base while backing it up as part of the daily maintenance.

is ever written to disk, it'll be zeroes not garbage.
Also, NULL the subscan pointer after freeing (and don't free if it's NULL).

is set: this insures that uninitialized msg-scan ptrs/cfg won't be
written to disk unless a successful logon()/getmsgptrs() was called first.
This probably fixes the sighting that echicken reported where a failed
SSH login caused his sub-scan config file (data/user/0001.subs) to contain
uninitialized/garbage values.
logout() could be called from multiple places (e.g. JS and Baja modules),
even before a successful login is completed, so this sighting is not
entirely impractical.

record in the node.dab - only the node(s) that have the requested user
number.
In sbbs_t::getsmsg() and ::getsmsg(), strip all invalid Ctrl-A attribute
codes (e.g. clear screen, pause, etc.) since short-messages (telegrams)
can come from external sources.

Double the duration to wait for client threads to terminate. Heck, this might
should be an infinite wait since "bad things" happen if the client thread
continues after a cleanup().

actual message number (rather than a 1-based message index offset) by using
#<number>, e.g. "smbutil r#3694" will read the message base starting at
message number 3694, if it exists.

Also documented the [-n] syntax for reading/listing messages less than
n days old.

with the terminal and mail servers' log output and provide more details
(e.g. on errors).

separate from the log text and is consistent with the mail server log
output.

alphabetized, so the indexes don't necessarily match the order (of timed
events) in SCFG.

text.
Use strcasestr() for message body/header-field text searches (simplify
the code) - not sure why we needed strip_ctrl(), so removed.

the tags (no yes/no prompt), and use the original message's tags as the
default value.

MSG_SUMMARY is currently never populated by anything.
MSG_TAGS is a new (optional) thing.

from both ends of the input string automatically and disallow (ignore)
more than one consecutive space character mid-string.
The returned value is still the non-trimmed string length - perhaps that
should be changed.

a message header.
Added "tags" and "summary" (previously missing) to the property fields
parsed when adding/writing a message header. This parse code is getting
particulary copy/pasta and should be converted to a table-driven loop
reusing the same logic.

message header.

Updated some comments in smbdefs.h too.

If a message sub-board is configured to "Allow Message Tagging"
(under Toggle Options in SCFG->Message Areas), then after a message is
posted (via the terminal server), the user will be prompted if they
want to tag the message with one or more space-separated tags. The no/yes
prompt can be skipp if desired by setting the TagMessageQ line in the
text.dat file to an empty string. There is currently no provision for
regular users to actually see/view the message tags (yet), but the sysop
or sub-op can view the tags in the message header with the 'H' sys/sub-op
command.

smb_nettype() now return "FidoNet" instead of "Fidonet" for NET_FIDO
(for not particularly good reason).

Fixed some funny typos in comments.

QWKnet call-outs. Hopefully help debug Mortifis' problem with QWKnet
call-outs.

(stops parsing/displaying upon Ctrl-Z) - this solves the SAUCE record
issue for sysops (e.g. using PabloDraw).

always include the text description of the last error and the line number.
The logging of the smb.file string is probably redundant since that path
will likely be included in the last_error string.

messages (and maybe files in the future).

confusing with 3 bool settings (in the sbbsecho.ini) to represent 4 valid
security requirement levels, so I attempted to simply the menu options to
make it easy for sysops.
BinkpAllowPlainText now defaults to true since the supported encryption method
isn't even an official FidoNet standard, yet.
I also added/updated some online help (F1) help text.
Added an "Exiting" popup (like SCFG) when exiting.