adjust Slideshow to not re-export printable<%>; improve docs for both Slideshow and Scribble

collects/scribblings/scribble/base.scrbl

@@ -27,14 +27,17 @@
 
 @title[#:tag "base"]{Base Document Format}
 
-@defmodulelang[scribble/base]{The @racketmodname[scribble/base] language
-provides functions and forms that can be used from code written either
-in Racket or with @elem["@"] expressions.
+@defmodulelang[scribble/base]{The @racketmodname[scribble/base]
+language provides functions and forms that can be used from code
+written either in Racket or with @elem["@"] expressions. It
+essentially extends @racketmodname[racket/base], except that top-level
+forms within a module using the @racketmodname[scribble/base] language
+are treated as document content (like @racketmodname[scribble/doclang]).
 
-The @racketmodname[scribble/base] name can also be used as a
-library with @racket[require], in which case it provides all of the same
-bindings, but without setting the reader or setting the default
-rendering format to the Racket manual format.}
+The @racketmodname[scribble/base] name can also be used as a library
+with @racket[require], in which case it provides only the bindings
+defined in this section, and it also does not set the reader or
+set the default rendering format to the Racket manual format.}
 
 Functions provided by this library, such as @racket[title] and
 @racket[italic], might be called from Racket as

collects/scribblings/slideshow/slideshow.scrbl

@@ -1,5 +1,6 @@
 #lang scribble/doc
-@(require "ss.ss")
+@(require "ss.ss"
+          (for-syntax racket/class))
 
 @(define paper-url "http://www.cs.utah.edu/plt/publications/jfp05-ff.pdf")
 
@@ -18,8 +19,10 @@ To get started, run the @exec{slideshow} executable, and click the
 To learn more about why Slideshow is cool, see also ``Slideshow:
 Functional Presentations'' @cite["Findler06"].
 
-@defmodulelang*/no-declare[(slideshow)]{Most of the bindings defined in
-the manual are provided by the @racketmodname[slideshow] language.}
+@defmodulelang*/no-declare[(slideshow)]{Most of the bindings defined
+in the manual are provided by the @racketmodname[slideshow] language,
+which also re-exports all of @racketmodname[racket] except for
+@racket[printable<%>] (due to backward-compatibility issues).}
 
 @table-of-contents[]
 

collects/slideshow/main.rkt

@@ -2,7 +2,9 @@
 (module main racket
   (require "base.ss"
            "pict.ss")
-  (provide (all-from-out racket
+  (provide (except-out (all-from-out racket
                                      "base.ss"
-                         "pict.ss")))
+                                     "pict.ss")
+                       printable<%>)))
+