Internal: aim to reduce number of package dependencies from ~25 to <20

[francisbarton]

If possible.

[francisbarton]

The packages are just in the Suggests section and are all related to various data preparation processes and vignettes, so I think my concern about number of dependencies is probably unnecessary actually.

Going to leave the issue open for now, in case there are ways we can streamline that list anyway.

[chrismainey]

I think the guidance for vignettes is to add packages to suggests, as the use doesn't have to build them on install, but CRAN needs to know to build them.

[francisbarton]

Understood - and I'm making an assumption that the rule of thumb for dependencies that I've seen cited around the web ("try to keep below 20") probably only applies to Depends, not Suggests - so as I said maybe we're fine here and can close the issue.