* remove ability to set depth formula on MeshDepthMaterial.

* remove depth formulas

* decouple PerspectiveCamera parameters in ObjectLoader. see comment: https://github.com/mrdoob/three.js/pull/8561/files/7eea5d47d86a6376175761cddab2742f17de177f#r59205742

* null -> undefined checking of data.view

* only export view if defined.

I noticed this was missing after updating from an older version of ColladaLoader.js. This fixes the face materialIndex not being set.

* WebGLProgram: Rewrote uniform name parser.

* Revised structured uniforms.

- Allowed arbitrary nesting
- Removed map iteration

This allows users to specify an offset angle for the alpha value. Can be used to set an initial view direction when the device orientation controls are called.

(Also ran it through whitespace checker)

This PR replaces the deprecated .center with .target for all
THREE.OrbitControls objects.

* working on depth texture

* working on depth texture

* support depth texture in webgl1 and webgl2

* fix comments

* reset build to avoid diff noise

* add check for webgl2 context

* fix depth texture example

* animation for example

* add file

* add depthTexture to WebGLRenderTarget

* ensure depth format returns correct GL parmaeter

* use null for initial depthTexture value

* add some commented out code

* remove non existent property "dynamic"

* colorsNeedUpdate required for face3 color updates

* documents groupsNeedUpdate

* document areaWeighted parameter of method computeVertexNormals

* Let ObjectLoader load extended PerspectiveCamera.

Part 2 - "Oh complexity, how have I missed you!"

* Let ObjectLoader ignore perspectiveCam.focalLength.

* Make Clock work on iOS without polyfill.

* Clock: Avoid adding up unnecessary rounding error.

0.001 does not have a finite binary float representation.

* add ability to specify on MeshDepthMaterial the type of depth packing one wants.

* depthRGBA -> clipZRGBA - more correct name.

* forgotten replace of depthRGBA -> clipZRGBA.

* add MeshDepthMaterial depthFormat + depthPacking.  Use equations compatible with z buffers.

* adopting MeshDepthMaterial instead of clipZRGBA.

* remove clipZRGBA shader (aka depthRGBA shader) as we can now use MeshDepthMaterial for it.

* remove some comments.

* enable skinning in MeshDepthMaterial, as it was enabled in depthRGBA material.

* remove unused shader.

* fix bug.

* fix bug in shadows with MEshDepthMaterial.

* remove unnecessary debug code.

* ensure that skinning and morphTargets propagate with MeshDepthMaterial.

* fix ssao example to use new MeshDepthMaterial.

* remove unused code.

* add method docs

intersectsBox method not documented.

* correct isEmpty method name

correct isEmpty method name

* special purpose materials.

* rename example from special_purpose -> channels.  Add camera controls.

* minor polish to webgl_materials_channels.

* add standard material with displacement, normal and ao to show contract with normal and depth materials.

* fix orthographic camera near/far bounds.

* remove double add of material_channels example.