Replace PATH_MAX with LN_PATH_MAX, #defined to (PATH_MAX+1).
Use mastr buffers instead of fixed-size in many places.
Change parseopt() to malloc conffile.
checkgroups.c applyfilter.c: Fix some memleaks.
configutil.c: Fix possible overrun in parse_line, strncpy result was not
0-terminated.
miscutil.c: chdirgroup: possible overrun fixed, mallocs storage now.
Change this _portably_ and _safe_ if it hurts perfomance.
nntpd.c: GROUP bogus.group may not change current group.  LISTGROUP other.group
did not work.