[plt-dev] at-exp and whitespace

JFYI, the reason I implemented it this way is that I was worried about
what would happen if any whitespace is allows.  I was worried that
something like this can be a common mistake:

  (define foo "blah")
  @text{ @foo @foo @foo
         [but not another @foo] }

The error will be reading this as:

  (define foo "blah")
  (text " " foo " " foo " " (foo but not another foo) " ")

For a while, I considered allowing only spaces (not newlines), but the
result is an awkward set of rules to parse @-forms, so I chose to go
with the simple and uniform option.

-- 
          ((lambda (x) (x x)) (lambda (x) (x x)))          Eli Barzilay:
                  http://www.barzilay.org/                 Maze is Life!