Whitelist option

[Tofandel]

While there is an exclude option, it would be great to also have a whitelist option where the prefix would only be added to the matching

[RadValentin]

I think it's a good idea but I don't have time ATM to work on this plugin, if someone wants to implement this functionality they have my full support. In the meantime, the transform option can be used as a temporary way to get whitelisting.