Add a method to fetch the center of a rect

geometry/src/rect.rs

@@ -155,6 +155,11 @@ impl RectF {
         self.0[3]
     }
 
+    #[inline]
+    pub fn center(self) -> Vector2F {
+        self.origin() + self.size().scale(0.5)
+    }
+
     #[inline]
     pub fn scale(self, factor: f32) -> RectF {
         RectF(self.0 * F32x4::splat(factor))