This tweak avoids adding extra space when the white-label font is
taller than the line it's attached to. It also makes the label
disappear in IE 6, but I think we can live with that.
For example, a syntactic form box is labeled with "SYNTAX". Forms
such as `defform' and `defthing' now support a `#:kind' option
for setting the label.
For example, if you make a multi-column table with a
`racketblock' in each column, then the columns size
to fit the code --- instead of forcing the table width
to match the page width and forcing each column to take
an equal share width.
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).
