lazy, force, delay in scheme/promise and scheme; clean up mzscheme some, and clean up the docs some

svn: r8053

original commit: 415cd0bf1529db4521b8372ebb21e76e6ff628be

collects/mzlib/foreign.ss

@@ -1557,11 +1557,11 @@
 ;; version that uses finalizers, but that leads to calling Scheme from the GC
 ;; which is not a good idea.
 (define killer-executor (make-will-executor))
-(define killer-thread
-  (delay
-    (thread (lambda () (let loop () (will-execute killer-executor) (loop))))))
+(define killer-thread #f)
+
 (define* (register-finalizer obj finalizer)
-  (force killer-thread)
+  (unless killer-thread
+    (set! killer-thread (thread (lambda () (let loop () (will-execute killer-executor) (loop))))))
   (will-register killer-executor obj finalizer))
 
 (define-unsafer unsafe!)

collects/scheme/private/old-procs.ss

@@ -8,7 +8,9 @@
 
   (#%provide make-namespace
              free-identifier=?*
-             namespace-transformer-require)
+             namespace-transformer-require
+             transcript-on
+             transcript-off)
 
   (define reflect-var #f)
   
@@ -33,4 +35,9 @@
          (free-identifier=? a b)))
 
   (define (namespace-transformer-require qrs)
-    (namespace-require `(for-syntax ,qrs))))
+    (namespace-require `(for-syntax ,qrs)))
+
+  (define (transcript-on filename)
+    (error 'transcript-on "unsupported"))
+  (define (transcript-off)
+    (error 'transcript-off "unsupported")))