make RFC3987 urirefs

[rijpma]

uriref() should create IRIs rather than URIs, so no percent encoding. See https://github.com/CLARIAH/iribaker, https://github.com/dgerber/rfc3987. R-pattern to replace may look like this "(?!(?:[a-zA-Z0-9._~-]|[\\xA0-\\uD7FF\\uF900-\\uFDCF\\uFDF0-\\uFFEF])|%[0-9a-fA-F][0-9a-fA-F]|[!$&'()*+,;=]|:|@|/)(.)" (for stringi::stri_replace_all_regex()), but check this. Consider using the useful bits of url-encode as well.

[rijpma]

https://stackoverflow.com/questions/44948085/what-is-the-difference-between-iri-and-uri-in-owl

https://stackoverflow.com/questions/1547899/which-characters-make-a-url-invalid

https://stackoverflow.com/questions/161738/what-is-the-best-regular-expression-to-check-if-a-string-is-a-valid-url