Remove $FreeBSD$: one-line sh pattern

Remove /^\s*#[#!]?\s*\$FreeBSD\$.*$\n/

Fix typos in the BSD License.

Be consistent with other usr.sbin programs w/respect to the copyright
wording ("All rights reserved."); I had the casing wrong on many instances.

Add new flags `-d' (sets debug=1) and `-D file' (sets debugFile) and
improve debugging initialization. Also fixup USAGE statements while we're
here. Also, change initialization of main program to _not_ change working
directory, allowing the debugFile to be relative without confusion.

Import bsdconfig(8) as a replacement for the post-install abilities of
deprecated sysinstall(8). NOTE: WITH_BSDCONFIG is currently required.

Submitted by: Devin Teske (dteske), Ron McDowell <rcm@fuzzwad.org>
Reviewed by: Ron McDowell <rcm@fuzzwad.org>
Approved by: Ed Maste (emaste)