[Engine request] Fluffle

[martinezjason]

Is your feature request related to a problem? Please describe.
Fluffle is a "reverse image search service specifically made for the furry community", which "attempts to find images submitted to it on sites like Fur Affinity, Twitter, e621 and more", according to its firefox extension's description page.

Describe the solution you'd like
According to its documentation, search can only be done through the POST form, no search by URL.

Describe alternatives you've considered
Partially supersetted by SauceNao, although I see a few sites in Fluffle's documentation that are not on SauceNao's.