title: Exported Collada file from Blender is split up into pieces when imported into SceneKit
body: <p>I have a terrain object made with Blender.
  When I export it using the COLLADA exporter and import the file into SceneKit, the terrain is split up into pieces (like 8 or 10).
  This makes it fairly complicated to apply textures and move the object.</p>
  
  <p>Any ideas why this is happening?</p>