Also take a stab at cleaning up BDECFLAGS and convert all uses of
NOSTR, NIL, NONE, NOVAR, NOGRP, NOGE to NULL. Also kill 'register' to
get diffs somewhat closer to OpenBSD/NetBSD.
There are no functional changes however.
Reviewed by: nra (visual inspection)
o remove panic() in favor of err(3) and use err(3) functions
consistently throughout
o use stat(2)'s S_IS* macros rather than S_IF*
o [r]index -> str[r]chr
o convert some static buffers to dynamic ones
o use real tempfiles rather than reopening the same templates
o rename some functions that clash with libc
o convert wait_status from union to int and use wait(2) status macros
o fix multiple potential buffer overflows
o fix a few comments
o add $FreeBSD$
Reviewed by: nra, nectar (earlier version)
