converting `\markuplist` to `\markup`

[Werner LEMBERG]

What's the proper way to convert a `\markuplist` to a `\markup`?
`lilypond-book` splits a top-level `\table` into separate lines; I
want to avoid that because it prevents fine-tuning of the vertical
spacing of rows.  Right now I do

```
\markup \column {
  \table ...
}
```


    Werner