[plt-scheme] reading a whole file

[Shriram Krishnamurthi]

The Cookbook version has a slight non-atomicity problem (the file size
may change between the FILE-SIZE and the READ-STRING).  I don't know
quite how that works out in the version Veer posted (presumably the
same problem, because FILE-SIZE is being called on the file*name*, not
on the port descriptor).  I guess file operation atomicity is
OS-specific anyway.

Shriram