debounce updateUrl; make debounce always execute a function call after at least one is dropped

this should also fix the issue where the cursor position sometimes ends up at the wrong position after you stop moving

static/framework.js

@@ -21,10 +21,19 @@ export function listen(...listenerSpecs) {
 
 export function debounce(time, fn) {
     let timeout = null;
+    let queued = null;
     return (...args) => {
         if (timeout == null) {
             fn(...args);
-            timeout = setTimeout(() => (timeout = null), time);
+            timeout = setTimeout(() => {
+                timeout = null;
+                if (queued != null) {
+                    fn(...queued);
+                    queued = null;
+                }
+            }, time);
+        } else {
+            queued = args;
         }
     };
 }

static/index.js

@@ -32,6 +32,7 @@ function updateUrl(session, viewport) {
     url.hash = `${session.wallId}&x=${Math.floor(viewport.panX)}&y=${Math.floor(viewport.panY)}&zoom=${viewport.zoomLevel}`;
     history.replaceState(null, "", url);
 }
+updateUrl = debounce(500, updateUrl);
 
 function readUrl(urlString) {
     let url = new URL(urlString);