Move additive CurveProjective operators to traits

src/groth16/tests/dummy_engine.rs

@@ -413,10 +413,6 @@ impl CurveProjective for Fr {
         self.0 = <Fr as Field>::double(self).0;
     }
 
-    fn add_assign(&mut self, other: &Self) {
-        AddAssign::add_assign(self, other);
-    }
-
     fn add_assign_mixed(&mut self, other: &Self) {
         AddAssign::add_assign(self, other);
     }

src/groth16/verifier.rs

@@ -1,6 +1,7 @@
 use ff::PrimeField;
 use group::{CurveAffine, CurveProjective};
 use pairing::{Engine, PairingCurveAffine};
+use std::ops::AddAssign;
 
 use super::{PreparedVerifyingKey, Proof, VerifyingKey};
 

src/multiexp.rs

@@ -5,6 +5,7 @@ use futures::Future;
 use group::{CurveAffine, CurveProjective};
 use std::io;
 use std::iter;
+use std::ops::AddAssign;
 use std::sync::Arc;
 
 use super::SynthesisError;