For HTML, the style used in the output of `racketblock' now
disables line wrapping, and the Rkt text styles inherit
line-wrap behavior. This doesn't solve the general problem
of code overflowing the horizontal space, but it makes the
failure mode usefully better.
A new 'vertical-inset nested-flow style is used by
`defproc', `defform', etc. It has no effect for HTML,
but it introduces suitable vertical space for Latex output
(in case you want to use `defproc' in a SIGPLAN-format
paper, for example).