title: How to dynamically update the resolution of the Shadow Map in THREE.js when changing resolution?
body: <p>I want to dynamically change the resolution of the shadows of a spotlight in THREE.js.  <a href="https://stackoverflow.com/questions/21031120/unable-to-get-a-directionallight-shadow-to-update-correctly">This</a> question first seems relevant but it is not about my issue. I change the parameters of shadowmap dynamically but this is not affecting the scene. Even when I add more mesh objects after this, it does not affect the shadows in the scene/light. When I use an initial value (256,256), it is applied but not after showing the scene.</p>
  
  <pre><code>light.shadowMapWidth = 2048; 
  light.shadowMapHeight = 2048;
  </code></pre>
  
  <p>I tries the following but it didn't work:</p>
  
  <pre><code>light.shadowMap.setSize(100,100)
  </code></pre>
  
  <p>When I change the light.position, the shadow is updated but the resultion is not updated. It seems to use the .shadowMapWidth property in the beginning during the initialisation only.</p>