2017-07-24: adapt header of unicode-math-fun to run with the Guile-based wisp

adapt header of unicode-math-fun to run with the Guile-based wisp

diff --git a/examples/unicode-math-fun.w b/examples/unicode-math-fun.w
--- a/examples/unicode-math-fun.w
+++ b/examples/unicode-math-fun.w
@@ -1,4 +1,7 @@
-#!/home/arne/wisp/wisp-multiline.sh 
+#!/usr/bin/env sh
+# -*- wisp -*-
+guile -L $(dirname $(dirname $(realpath "$0"))) -c '(import (wisp-scheme) (language wisp spec))'
+exec guile -L $(dirname $(dirname $(realpath "$0"))) --language=wisp -s "$0" "$@"
 ; !#
 
 ;; Having fun with unicode and math :)