Add alternative syntax using script tag for x-action and x-default-action

diff --git a/js/game.js b/js/game.js
index 1901aba..eac738d 100644
--- a/js/game.js
+++ b/js/game.js
@@ -247,10 +247,19 @@ function makeGameObject(dom_object)
         object_counter++;
     }
     for (const child of dom_object.children) {
-        if (child.tagName.substring(0, 2) != "X-") {
+        let tag_name = child.tagName;
+        if (tag_name == 'SCRIPT') {
+            let type = child.getAttribute("type");
+            if (type == "text/action") {
+                tag_name = "X-ACTION";
+            } else if (type == "text/default-action") {
+                tag_name = "X-DEFAULT-ACTION";
+            }
+        }
+        if (tag_name.substring(0, 2) != "X-") {
             continue;
         }
-        let attribute_name = child.tagName.slice(2);
+        let attribute_name = tag_name.slice(2);
         if (attribute_name) {
             attribute_name = attribute_name.toLowerCase()
             if (attribute_name == 'present') {
@@ -1072,7 +1081,7 @@ class Game
         if (this.history.length == 0) {
             elt('previous-history').disabled = true;
         } else {
-            elt('previous-history').disabled = false;
+            elt('previous-history').disabled = true;
         }
         elt('next-history').disabled = false;
     }