[plt-scheme] v4.0 reference documentation complete

In the process of porting and writing documentation for version 4.0, we
recently reached a milestone: all of the reference documentation is now
in place!


Special thanks to the following individuals who helped port old
documentation:

 Yavuz Arkun, Filipe Cabecinhas, Richard Cleis, Will Farr, Geoff
 Knauth, Grant Rettke, David Van Horn, Doug Williams, and Danny Yoo.

As you can see from

 http://www.cs.utah.edu/~mflatt/tmp/doc-to-do.txt

many helped by porting multiple "doc.txt" files to Scribble format.


We still have plenty of work to do on documentation. Notably, "Guide"
still has many empty sections, and "Teach Yourself Scheme in Fixnum
Days" is a temporary casualty of the conversion. (Chapters 1-2 of
"Guide" cover some of the same material as "TYSiFD", but nowhere near
all.)

Actually, the overview and tutorial material will never be finished,
because there's always more to write and always parts to improve. But
the reference material is now "finished" in the sense that you
shouldn't have to fall back on v372 documentation.


Meanwhile, we're working on better searching support within the
browser. Stay tuned...


Matthew