Function doiUrl( doi )

Description:
Maps a DOI (Digital Object Identifier) to its dislay URL. If the supplied string does not appear to be a DOI, null will be returned.

If the supplied string appears to be a DOI, it strips any "doi:" prefix if present, prepends the string "https://doi.org/", and performs any character escaping that is required.

Parameters:
doi (String)
DOI string, with or without "doi:" prefix
Return Value (String):
display URL pointing at DOI content, or null if it doesn't look like a DOI
Example:
doiUrl("10.3390/informatics4030018") = "https://doi.org/10.3390/informatics4030018"
See Also:
https://www.doi.org/
Signature:
String doiUrl(String)