title: VSCode - gray out unused imports
body: <p>Is it possible to configure VSCode so that it displays unused import as grayed?
  I have VSCode 1.21.0, using Typescript 2.7.2 </p>
  
  <p>I found and tried several setups but none worked for me. Based on this <a href="https://stackoverflow.com/questions/47539259/how-can-i-show-unused-imports-locals-in-green-warning-in-vscode-rather-than-r">link</a> it should have been possible since version 1.19.0</p>
  
  <p>I tried setting tsconfig as described <a href="https://github.com/Microsoft/vscode-tslint/issues/219" rel="noreferrer">here</a> but the only effect was lots of error during compilation.</p>
  
  <p>It seems to be so basic requirement that I would even consider it as default setting. It is definitely possible in other editors (e.g. WebStorm). I love VSCode but I'm really missing this feature.</p>