Move simplified string-utf8? to util-utf8.

src/util-utf8.scm

@@ -44,6 +44,8 @@
   utf8-string->list
   list->utf8-string
 
+  string-utf8?
+
   util-utf8-tests!
   )
 
@@ -272,6 +274,12 @@
 	 (loop (cdr lst)
 	       (prepend-unicode-char-to-utf8-list (car lst) res)))))
 
+ ;; Returns true, if given string contains UTF-8 characters
+ (define (string-utf8? s)
+   (let ((asciilen (string-length s))
+	 (utf8len (utf8-string-length s)))
+     (not (= asciilen utf8len))))
+
  ;; Module self-tests
  (define (util-utf8-tests!)
    (run-tests
@@ -303,6 +311,8 @@
     (test-equal? utf8-string-next-char
 		 (utf8-string-next-char "ěščř" 2)
 		 4)
+    (test-true string-utf8? (string-utf8? "ěščř"))
+    (test-false string-utf8? (string-utf8? "Hello World!"))
     ))
 
  )