enhanced test to keep a permanent list of UTF files in tests/UTF_Files

Jenkinsfile

@@ -184,7 +184,8 @@ Changelog of Git Changelog.
       stage('check for UTF-8 files') {
         steps {
           sh '''echo "$(find . -type f -exec file {} \\;)" > FileList
-            grep -v ASCII FileList | grep -v git'''
+            mkdir tests
+            echo  "$(grep -v ASCII FileList | grep -v git)" > tests/UTF_Files'''
         }
       }