Add Group::mul_by_generator

Adds a provided method to the `Group` trait for performing
multiplication by the generator.

The use case is overriding this method in the event that precomputed
scalar multiplication tables are available, which may be conditional
depending on crate features like `alloc` or feature-gated static
precomputed tables.

Author: tarcieri

src/lib.rs

@@ -90,6 +90,12 @@ pub trait Group:
     /// Doubles this element.
     #[must_use]
     fn double(&self) -> Self;
+
+    /// Multiply by the generator of the prime-order subgroup.
+    #[must_use]
+    fn mul_by_generator(scalar: &Self::Scalar) -> Self {
+        Self::generator() * scalar
+    }
 }
 
 /// Efficient representation of an elliptic curve point guaranteed.