Fix alt-duplicate (#326)

We need to unselect all the previous elements and select all the new ones. Also made sure that the shape is regenerated when the element is duplicated

src/element/newElement.ts

@@ -37,6 +37,7 @@ export function newElement(
 
 export function duplicateElement(element: ReturnType<typeof newElement>) {
   const copy = { ...element };
+  delete copy.shape;
   copy.id = nanoid();
   copy.seed = randomSeed();
   return copy;