Fix the renderList sort function to be truly stable

Multiple objects can have the same id. Using that id to compare the render
objects makes the sort function unstable. Use the webgl object's index in the
render list instead. That number is guaranteed to be unique.

This fixes #2966.
WebGLRenderer: ids need to be sorted in reverse.
Implemented hierarchy to SceneLoader2.
SceneLoader2 wrongly using SceneExporter2 constructor.
Added morphTargets support to MeshNormalMaterial. Fixes #3200.
Updated builds.
Merge remote-tracking branch 'zz85/master' into dev
Updated builds.