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).

Each function that requires a temp string variable, now has its own "tmp" local variable.