Added HOST and IP keywords to allow restricted access/privileges to/for
specific remote hostnames or IP addresses (wildcards allowed).
All string-argument type ARS keywords (e.g. SHELL, PROT, etc.) now support .can
style wildcards.
The current remote client is now used for protocol, host, and IP ARS checking,
when available, so this requires passing the client pointer around (which
explains why so many files are touched by this change) and takes care of a
long standing to-do item (the user's 'modem' value was used for the PROT
value checking, which was not always correct).

by properly const-ifying the appropriate functions and variables.

Not yet tested on Win32

single function.
* editfile() now modifies a temporary copy of the file which solves 2 problems:
A. editors restricted to the temp dir (e.g. PICO) can now be used to edit other
    files (e.g. sig files)
B. DOS editors can now be used to edit files with long filenames
    (e.g. .plan files)

Uploads in E-mail is set to "No". This option has been in SCFG for 10(+?) years
and was never used. :-)

instead of user number (allow the higher level to determine what constitutes
feedback or not).

credits, and minutes - basically wrappers for adjustuserrec().

no need to do manual initialization here.

forward their mail to a valid netmail address.

an unlimited number of messages (within SMB limits), by default.

and net_addr() to smb_netaddr().

call smb_freemsgdat/dfields *after* logging smb.last_error.

for additional tracking information.
Created DLL-exported msg_client_hfields() in postmsg.cpp as a common function
to add these client tracking header fields.

used to trace message origins for security reasons.

smb_read() will now retry the read operation if the read fails with an errno of
DEADLOCK (occurs on Unix if a Win32 system has the bytes already locked).

the system timezone, which handles the optional automatic toggle of the DST bit
for US-zones in real-time. Previously, the DST flag would only be toggled when
loading configuration files, now it will happen in real-time.

smb_hfield_append_str() used for creating and appending ASCIIZ header fields.
These functions handle the string-length calculation automatically.

etc).

if text/menu/*prot.asc does not exist.

temp dir, move it.

outside the sbbs_t class).