Add ed(1) - the standard text editor

Makefile

@@ -92,6 +92,7 @@ BIN =\
 	dirname\
 	du\
 	echo\
+	ed\
 	env\
 	expand\
 	expr\

README

@@ -30,6 +30,7 @@ The following tools are implemented:
 =*|o dirname     .
 =*|o du          .
 =*|o echo        .
+   o ed          .
 =*|o env         .
 #*|o expand      .
 #*|o expr        .

TODO

@@ -7,7 +7,7 @@ at
 awk
 bc
 diff
-ed
+ed manpage
 install
 patch
 pathchk

ed.1

@@ -0,0 +1,9 @@
+.Dd 2015-12-14
+.Dt ED 1
+.Os sbase
+.Sh NAME
+.Nm ed
+.Nd text editor
+.Sh SYNOPSIS
+.Nm
+is the standard text editor.