"open" takes a mangled filename, and as is usual with mangled names, it is
pointed to by DI, not SI.

struc/endstruc effectively push/pop the context around them.

Small Perl script to postprocess the listfile and show absolute addresses
instead of section-relative.  This only applies to the main address, not
to addresses in bracketed fields.

We were using an open-coded string copy with the wrong length.  Use
strcpy instead.

Make sure we capture only the first instance of the UUID, in case
the server does something silly like send back its own UUID.

From a brief look around the Internet, it seems UUID is more commonly
written in lower case (still with the funny dash pattern, though.)  Stick
with that convention.

Also, unify upper-vs-lower-case hexadecimal string production.

- Generate a config file name based on the UUID as well as previous types;
- Get better about picking up client identifier option;
- Clean up config file name generation.

The first byte of the client identifier is the identifier type.
Look at that one first and only copy if it matches the hardware ARP type.