In jsonlite::toJSON, use na="null" so there are no "NA" values
Revise split_whitespace to avoid spaces within quotes; add tests
Use strip_whitespace on chartOpts
Further improvement of strip_whitespace

 - To avoid dealing with individual single quotes as in "Don't do this",
   I'm only protecting text within double-quotes.

 - Nested double-quotes will still be a problem.