Make Renderer private

For #1587 

* Breaking changes
  * Replaced `Scene.createTextureAtlas` with `new TextureAtlas`.
  * Removed `Tipsify`, `FrustumCommands`, and all `Renderer` types (except noted below) from the public Cesium API.  These are still available but are not part of the official API and are likely to change in future versions.    
  * For AMD users only: moved `PixelFormat` from `Renderer` to `Core`.  Moved the following from `Renderer` to `Scene`: `TextureAtlas`, `TextureAtlasBuilder`, `BlendEquation`, `BlendFunction`, `BlendingState`, `CullFace`, `DepthFunction`, `StencilFunction`, and `StencilOperation`.
* Added `interleave` option to `Primitive` constructor.