Add SEND-ERROR, that sends an error.

scheme/httpd/surflets/packages.scm

@@ -72,6 +72,7 @@
   (export send/suspend			;send and suspend
 	  send/finish			;send and finish
 	  send				;just send (no finish, no suspend)
+	  send-error			;send error response
 	  set-surflet-data!
 	  get-surflet-data
 	  adjust-timeout		;adjusts timeout of current session
@@ -151,6 +152,7 @@
   (export send/suspend
 	  send/finish
 	  send
+	  send-error
 	  send-html/suspend
 	  send-html/finish
 	  send-html

scheme/httpd/surflets/surflet-handler.scm

@@ -280,6 +280,12 @@
 (define (send response)
   (shift unused (make-http-response response)))
 
+;; REQ may be #f in some (most) cases.
+(define (send-error status-code req . messages)
+  (shift unused (apply make-error-response 
+		       (cons status-code 
+			     (cons #f messages)))))
+
 (define (make-http-response response)
   (cond
    ((surflet-response? response)