Add reversible new item swap

index.html

@@ -104,6 +104,11 @@
           <div><span>DPS change</span><strong id="replacementDpsDelta">0</strong></div>
           <div><span>Regen change</span><strong id="replacementRegenDelta">0</strong></div>
         </div>
+        <div class="swap-actions">
+          <button id="swapNewItem" type="button">Swap in new item</button>
+          <button id="swapBackNewItem" type="button" class="secondary" disabled>Swap back</button>
+          <span id="swapStatus" class="status"></span>
+        </div>
       </section>
 
       <section>