sh(1): make it the default shell for the root user

In the recent history sh(1) has gain the missing features for it to
become a usable interractive shell:
- command completion
- persistent history support
- improvements on the default bindings in emacs mode
- improvements in the vi mode (repect $EDITOR)
- print a newline when exiting via ^D
- default prompt and improvements on how PS1 can be configured
- and more.

This changes also simplifies making tiny freebsd images with only sh(1)
as a shell

UPDATING

@@ -27,6 +27,12 @@ NOTE TO PEOPLE WHO THINK THAT FreeBSD 14.x IS SLOW:
 	world, or to merely disable the most expensive debugging functionality
 	at runtime, run "ln -s 'abort:false,junk:false' /etc/malloc.conf".)
 
+20211020:
+	sh(1) is now the default shell for the root user. to force root to use
+	the csh shell, please run the following command as root:
+
+	$ chsh -s csh
+
 20211004:
 	Ncurses distribution has been split between libtinfow and libncurses
 	with libncurses.so becoming a linker (ld) script to seamlessly link

etc/master.passwd

@@ -1,6 +1,6 @@
 # $FreeBSD$
 #
-root::0:0::0:0:Charlie &:/root:/bin/csh
+root::0:0::0:0:Charlie &:/root:/bin/sh
 toor:*:0:0::0:0:Bourne-again Superuser:/root:
 daemon:*:1:1::0:0:Owner of many system processes:/root:/usr/sbin/nologin
 operator:*:2:5::0:0:System &:/:/usr/sbin/nologin