[9fans] plan9port: recent changes

[Russ Cox <russcox@gmail.com>]

Lots of little changes in the past week or so: autoindent for sam,
better label handling in awd et al., new diff flags -c and -a,
various stack overflow fixes (*cough* X11 *cough*), programs
should work better with SIGTSTP, SIGTTIN, and SIGTTOU,
lots of little bug fixes.

The big new additions are factotum and various supporting
libraries and programs.

Thanks to Lucho, plan9port now has a working factotum
that can be used with 9p to access files on protected servers:

	ibook=; factotum
	ibook=; sources='tcp!sources.cs.bell-labs.com!9fs'
	ibook=; 9p -a $sources read plan9/adm/users

	!adding key: role=client proto=p9sk1 dom=outside.plan9.bell-labs.com
	user[rsc]: bozo
	password:
	!
	-1:adm:adm:bootes
	0:none:adm:
	1:tor:tor:
	2:glenda:glenda:
	9999:noworld::
	10000:sys::
	10001:upas:upas:
	10002:bootes:bootes:
	ibook=; 9p -a $sources read plan9/NOTICE
	Copyright © 2002 Lucent Technologies Inc.
	All Rights Reserved
	ibook=; 

Over the weekend I added DSA and RSA signature support
to factotum and used them to implement an ssh-agent front
end for factotum:

	l=; factotum
	secstore password: 
	l=; eval `{9 ssh-agent}
	l=; ssh tux
	tux=; ^D
	l=; 

It's hard to see, but ssh used factotum via the ssh-agent
interface to authenticate to tux.  Also hard to see is the fact
that this is using SSH version 2 keys (SSH1 is also supported),
so this setup is ahead of Plan 9.

(Sadly, it's not too easy to move the DSA and RSA support back
into Plan 9, firstly due to the lack of an SSH2 client.  Also the 
factotum is completely different--simpler--inside.)

Enjoy.
Russ