Add mes and mescc-tools-extra

mescc-tools-extra contains two important tools:
- cp
- chmod

mes first builds itself from a mes 0.21 seed as used by guix, and then
builds a mes 0.22 and then mes 0.22 using that created mes 0.22.

It does /not/ use bootstrap.sh as we don't have a proper shell at this
point, it has been manually adapted for kaem.

sysa/mes-0.22/scaffold/boot/50-string-join.scm

@@ -0,0 +1,50 @@
+;;; GNU Mes --- Maxwell Equations of Software
+;;; Copyright © 2018 Jan (janneke) Nieuwenhuizen <janneke@gnu.org>
+;;;
+;;; This file is part of GNU Mes.
+;;;
+;;; GNU Mes is free software; you can redistribute it and/or modify it
+;;; under the terms of the GNU General Public License as published by
+;;; the Free Software Foundation; either version 3 of the License, or (at
+;;; your option) any later version.
+;;;
+;;; GNU Mes is distributed in the hope that it will be useful, but
+;;; WITHOUT ANY WARRANTY; without even the implied warranty of
+;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;;; GNU General Public License for more details.
+;;;
+;;; You should have received a copy of the GNU General Public License
+;;; along with GNU Mes.  If not, see <http://www.gnu.org/licenses/>.
+
+(cond-expand
+ (guile)
+ (mes
+  (define (cons* . rest)
+    (if (null? (cdr rest)) (car rest)
+        (cons (car rest) (core:apply cons* (cdr rest) (current-module)))))
+
+  (define (apply f h . t)
+    (if (null? t) (core:apply f h (current-module))
+        (apply f (apply cons* (cons h t)))))
+
+  (define (append . rest)
+    (if (null? rest) '()
+        (if (null? (cdr rest)) (car rest)
+            (append2 (car rest) (apply append (cdr rest))))))
+
+  (define (string . lst)
+    (list->string lst))
+
+  (define (map1 f lst)
+    (if (null? lst) (list)
+        (cons (f (car lst)) (map1 f (cdr lst)))))
+
+  (define map map1)))
+
+(define (string-join lst infix)
+  (if (null? (cdr lst)) (car lst)
+      (string-append (car lst) infix (string-join (cdr lst) infix))))
+
+(if (string=? (string-join '("foo" "bar") "/") "foo/bar")
+    (exit 0))
+(exit 1)