Added collapsible skill group & volatile storage.

system/scripts/storage.js

@@ -0,0 +1,39 @@
+/**
+ * Volatile Storage - Store things like collapsible state (refresh kill it)
+ */
+export class Storage {
+    store = new Map();
+
+    /**
+     * Get list of active keys for this app
+     * @param  {string} app
+     * @return {string[]}
+     */
+    getAppKeys(app) {
+        if (!this.store.has(app)) {
+            return [];
+        }
+        return Array.from(this.store.get(app).keys());
+    }
+
+    /**
+     * Toggle a key for this app
+     * @param {string} app app name, ex "actor-Zca44Nv7ydMcNN9p"
+     * @param {string} key Key name, ex "toggle-skill-category-martial"
+     */
+    toggleKey(app, key) {
+        if (this.store.has(app)) {
+            const appMap = this.store.get(app);
+            if (appMap.has(key)) {
+                appMap.delete(key);
+            } else {
+                appMap.set(key, true);
+            }
+        } else {
+            // Create app map
+            const appMap = new Map();
+            appMap.set(key, true);
+            this.store.set(app, appMap);
+        }
+    }
+}