title: Three.js no shadows on ShaderMaterial
body: <p>I'm creating terrain editor with three.js and i have encountered few problems.
  First. Shadows renders on MeshLambertMaterial, but it wont on ShaderMaterial.
  Second. How to change object's material (from lambert to shader) on runtime?
  Here's demo of my editor: <code>http://78.62.160.169/webgl/editor/</code>
  And source code: <code>http://78.62.160.169/webgl/editor/script.js</code></p>