title: How to render errors / warnings directly inside editor
body: <p>I am looking for setting / extension, which enable to render errors / warnings inside editor viewlet instead of hover and red underscore.</p>
  
  <p><img src="https://user-images.githubusercontent.com/9638156/51089978-4f007f80-1786-11e9-8abf-1fa9c296d014.gif" alt="Desired behaviour"></p>
  
  <p><img src="https://i.imgur.com/ctQo66k.png" alt="Actual behaviour"></p>