Add optional arguments to ADJUST-TIMEOUT! and SESSION-ADJUST-TIMEOUT!

This argument defaults to OPTIONS-SESSION-LIFETIME and represents
the life-time in seconds for the session.

scheme/httpd/surflets/packages.scm

@@ -244,6 +244,7 @@
 	httpd-logging			;HTTP-SYSLOG
 	httpd-requests			;requests from httpd
 	httpd-responses			;replies for httpd 
+	let-opt				;:OPTIONAL
 	locks				;MAKE-LOCK et al.
 	profiling			;PROFILE-SPACE
 	rt-module-language		;get structures dynamically

scheme/httpd/surflets/surflet-handler.scm

@@ -323,7 +323,12 @@
  
 ;;; SESSION-ADJUST-TIMEOUT!
 ;; Resets time-to-die of session indicated by its SESSION-ID number.
-(define (session-adjust-timeout! session-id)
+(define (session-adjust-timeout! session-id . maybe-time-to-live)
+  (really-session-adjust-timeout! 
+   session-id 
+   (:optional maybe-time-to-live (options-session-lifetime))))
+
+(define (really-session-adjust-timeout! session-id time-to-live)
   (obtain-lock *session-table-lock*)
   (let* ((session (table-ref *session-table* session-id))
 	 (memo (session-memo session))
@@ -339,9 +344,13 @@
   (release-lock *session-table-lock*))
 
 ;;; ADJUST-TIMEOUT!
-;; Resets time-to-die of current session.
-(define (adjust-timeout!)
-  (session-adjust-timeout! (instance-session-id)))
+;; Resets time-to-die of current session. The argument must be
+;; optional as PLT does not have it.
+(define (adjust-timeout! . maybe-time-to-live)
+  (really-session-adjust-timeout! 
+   (instance-session-id) 
+   (:optional maybe-time-to-live
+	      (options-session-lifetime))))
 
 ;;; RESET-SESSION-TABLE!
 ;; Clears the *SESSION-TABLE* (locking)