Add grenade counter

src/index.js

@@ -206,6 +206,8 @@ window.addEventListener('load', () => {
     el.addEventListener('click', () => game.setFiringArc(el.dataset.size))
   );
 
+  document.querySelector('.set-grenade').addEventListener('click', () => game.setGrenade());
+
   recordSheetVisibility.addEventListener('input', e => {
     let divs = document.querySelectorAll('#content div');