update procedure docs for programs, lambda*, case-lambda

* module/system/vm/program.scm: Export the arity things again, and
  program-arity. Why not.

* doc/ref/api-procedures.texi (Compiled Procedures): Update for current
  API.
  (Optional Arguments): Update to assume lambda* and define* are always
  available, and (ice-9 optargs) is now the ghetto.
  (Case-lambda): Now here, moved from SRFI-16 docs. Also docs
  case-lambda*.

* doc/ref/srfi-modules.texi: Point to core case-lambda docs.

module/system/vm/program.scm

@@ -32,8 +32,12 @@
             program-name
 
             program-bindings program-bindings-by-index program-bindings-for-ip
-            program-arities program-arguments program-lambda-list
-           
+            program-arities program-arity arity:start arity:end
+
+            arity:nreq arity:nopt arity:rest? arity:kw arity:allow-other-keys?
+
+            program-arguments program-lambda-list
+            
             program-meta
             program-objcode program? program-objects
             program-module program-base program-free-variables))
@@ -112,7 +116,6 @@
 (define (arity:allow-other-keys? a)
   (pmatch a ((_ _ ,nreq ,nopt ,rest? (,aok . ,kw)) aok) (else #f)))
 
-;; not exported; should it be?
 (define (program-arity prog ip)
   (let ((arities (program-arities prog)))
     (and arities