Fix stanek leaking classes

src/CotMG/ActiveFragment.ts

@@ -68,13 +68,7 @@ export class ActiveFragment {
   }
 
   copy(): ActiveFragment {
-    // We have to do a round trip because the constructor.
-    const fragment = FragmentById(this.id);
-    if (fragment === null) throw new Error("ActiveFragment id refers to unknown Fragment.");
-    const c = new ActiveFragment({ x: this.x, y: this.y, rotation: this.rotation, fragment: fragment });
-    c.highestCharge = this.highestCharge;
-    c.numCharge = this.numCharge;
-    return c;
+    return Object.assign({}, this);
   }
 
   /**

src/CotMG/Fragment.ts

@@ -76,13 +76,7 @@ export class Fragment {
   }
 
   copy(): Fragment {
-    return new Fragment(
-      this.id,
-      this.shape.map((a) => a.slice()),
-      this.type,
-      this.power,
-      this.limit,
-    );
+    return Object.assign({}, this);
   }
 }