ed: upgrade to 1.6

ed: upgrade to 1.6

This patch is to upgrade ed to 1.6, and the change of license checksum is because

the diff between two ed.h files:

3c3,4
<     Copyright (C) 1993, 1994, 2006, 2007, 2008, 2009, 2010
---
>     Copyright (C) 1993, 1994 Andrew Moore, Talke Studio
>     Copyright (C) 2006, 2007, 2008, 2009, 2010, 2011, 2012

the diff between two main.c files:

2c2
<     Copyright (C) 1993, 1994, 2006, 2007, 2008, 2009, 2010
---
>     Copyright (C) 2006, 2007, 2008, 2009, 2010, 2011, 2012
46d45

Signed-off-by: Shane Wang <shane.wang@intel.com>