nular or NULL.

DIR <code>) are now handled correctly. The PROT (protocol) keyword never worked
correctly.
Some ambiguities (e.g. "PROT NOTIFY" and "PROT NOT IFY") are now handled more
gracefully. White-space is now required after AND/OR/EQUAL/NOT if the next char
is a letter. All the examples in http://synchro.net/docs/security.html
still work as documented.

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).

ULM (uploaded megabytes), and DLK and DLM (for downloaded K/Mbytes).

* ULS - uploaded files
* ULB - uploaded bytes
* DLS - downloaded files
* DLB - downloaded bytes

... so now Phil can have a "true" 1:4 upload/download file ratio requirement by
using an ARS of "DLS NOT 4 OR UDFR 25"

* GUEST (shorthand for "REST G")
* QNODE (shorthand for "REST Q").
They're not really much shorter, but the intended function is more clear to the
sysop.

correctly for the BBS (e.g. "Telnet" and "RLogin") until the chk_ar function is
changed to accept a client_t argument.