ambientOcclusion -> ao per @WestLangley feedback here: https://github.com/mrdoob/three.js/pull/6263#issuecomment-83794671 #2

remove material.ambient from everything per discussion here: https://github.com/mrdoob/three.js/pull/5741#issuecomment-67893202

Fixes #5570

Added support for using a separate alpha map with MeshBasicMaterial, MeshLambertMaterial, and MeshPhongMaterial, and updated the OBJ converter to set materials as transparent if an alpha map is defined.

Specular map works like it used to for normal map shader. It is assumed to be a grayscale texture.

For Phong specular map value modulates specular term strength and environment map reflection strength.

For Lambert and Basic materials specular map affects just environment map reflection strength (as these have no specular term).

Still not very sure how environment mapping and specular term should interact with each other.

Changed vertexColor default from "false" to "THREE.NoColor" constant. Added missing morphNormals parameter to ShaderMaterial.

It seems to work, though not sure yet how to handle some things. Also for the moment it's implemented just for Lambert material.

As per discussion in #1207

With a little twist - per color component mixing of regular and wrap-around lightings.

Removed diffuse color influence on ambient term in Phong. This was causing texture disappearance when diffuse color was black.

Made Lambert more similar to Phong: now it also has ambient color parameter. Before ambient light was affecting Lambert as if ambient color was always 0xffffff.

Moved materials/RenderTarget.js ⟶ renderer/WebGLRenderTarget.js

Refactored everything to use CamelCase naming for properties. Plus some smaller fixes here and there.

Went through all examples, all should work.

JSON files exported from Blender / converted from OBJ files still use underscored property names internally. I don't know, should these also be changed?

I don't remember when was the last time I used them. Current Web Developer Tools do this already for you.

Color::updateRGBA ⟶ Color::updateRGB

- getters/setters are no more in Vector3
  - object hierarchies thus don't use "isDirty"
  - this was completely killing performance for anything that was touching a lot of Vector3 like creation of meshes and dynamic buffers
  - even without this, performance of hierarchies went up (a lot)

- objects do not get passed renderer anymore
  - camera was almost also removed, but this is useful for LOD (though there may be some cleaner way to do this?)

- material ids are now unified, this makes "geometry.sortFacesByMaterial" faster (thus scene init / GUI blocking is shorter)

- all WebGL examples should work now (render-to-texture has weird lights and in some camera control feels different)

- CanvasRender still broken, despite many efforts :(
   - currently only points and lines work, faces don't show up. I think this may need assistance from mrdoob.