Keep the server information fields semantically distinct after replacing
the legacy KOAN/14-Jun-03 strings.
The revision string now reports the Mars NWE release version, for
example:
Mars NWE 0.99.pl28
and the separate revision-date field is populated from a CMake-provided
build date in the traditional NetWare-style format, for example:
27-May-26
The build date can be overridden through CMake for reproducible builds;
otherwise it defaults to the current UTC build date.
Replace the old hard-coded server description date with a Mars NWE
version string built from the existing _VERS_H_, _VERS_L_ and _VERS_P_
build macros.
WHOAMI and similar clients display this value in the line:
Server <name> is running <description>.
Instead of reporting the legacy fixed value "14-Jun-03", the server now
reports a stable release-style description such as:
mars-nwe-0.99.pl28
Also advance the response buffer after writing the revision string so the
description field does not overwrite the previous field.
