Display the splash screen only until the theme manager is ready.

The full animation was awesome the first several times, then started getting repetitive every single time the page was refreshed.

packages/apputils-extension/src/index.ts

@@ -169,7 +169,7 @@ const themes: JupyterLabPlugin<IThemeManager> = {
     const disposable = splash.show();
     const dispose = () => { disposable.dispose(); };
 
-    manager.ready.then(() => { setTimeout(dispose, 2500); }, dispose);
+    manager.ready.then(dispose, dispose);
 
     return manager;
   },

packages/apputils-extension/style/splash.css

@@ -18,7 +18,7 @@
 
 
 .splash-fade {
-  animation: .5s fade-out forwards;
+  animation: .2s fade-out forwards;
 }