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.
original commit: b7afb3cf8fbbf448af18805db2f32c130ba4d47b
Also, updates some of the mzlib files to point at `racket/*' libraries
rather than to `scheme/*' ones.
original commit: ac26fe75546b5182d78f18c2cd882f0f440849e2
