Giorgio is quite adamant (pun intended) about not implementing whitelisting support:
http://giorgiocalderolla.com/wipr-and-whitelisting.html
Apart from that it's:
That's quite a lot for a "simple" content blocker IMO.
I think the new content blocking mechanism (introduced by Apple in El Capitan) can do this. The link above mentions some "new adblockers" in the first post, but you'd have to read through all pages to find more.
For wipr specifically, I saw that the developed has talked about whitelisting a year ago http://giorgiocalderolla.com/wipr-and-whitelisting.html.
Hi! I'm him. Ask away :) Or you can find my email address here: http://giorgiocalderolla.com/support.html
I'm currently running a beta for Wipr 1.1 which will let you contact me straight from the app. If anyone would like to join the beta, let me know!