slight bezier optimization

src/parse/pos2.rs

@@ -9,6 +9,11 @@ pub struct Pos2 {
 }
 
 impl Pos2 {
+    #[inline]
+    pub fn zero() -> Self {
+        Self::default()
+    }
+
     #[inline]
     pub fn length_squared(&self) -> f32 {
         self.dot(*self)