I mailed the developer at highlight, and he says the following: there indeed is a conflict with a Mint package, see: http://andre-simon.de/dokuwiki/doku.php?id=en:installation_linux
There I could see : "There is a system script called highlight which is located in a preferenced path:
Calling this script with the true highlight command line options will have no effect."
Can anyone tell me if this /usr/local/bin/highlight that is in Mint by default, can be deleted without serious consequence?
I would like the other highlight program to work as intended for previews in the file manager ranger http://ranger.nongnu.org/