identity -> zero for Affine

Author: Pratyush

src/groups/curves/short_weierstrass/mod.rs

@@ -209,7 +209,7 @@ where
         let (x, y, z) = match f() {
             Ok(ge) => {
                 let ge = ge.into_affine();
-                if ge.is_identity() {
+                if ge.is_zero() {
                     (
                         Ok(P::BaseField::zero()),
                         Ok(P::BaseField::one()),

src/groups/curves/short_weierstrass/non_zero_affine.rs

@@ -75,7 +75,7 @@ where
                 .double()
                 .into_affine();
             // Panic if the result is zero.
-            assert!(!result.is_identity());
+            assert!(!result.is_zero());
             Ok(Self::new(F::constant(result.x), F::constant(result.y)))
         } else {
             let (x1, y1) = (&self.x, &self.y);