* Add a BufferGeometry based Subdivision Modifier

This started from the original subdivision modifier, and works in the
same way except it has different output - and is much MUCH faster and
far easier on RAM. (From >1m and >3gb (queue crashing browsers) to <10
seconds and <500mb on my tests).

Expected input: Index'd Buffer Geometry or THREE.Geometry - with uv's.
Output: Unindex'd Buffer Geometry.

Also introduced is a class I call the 'TypedArrayHelper' which provides
THREE objects (Such as Face, Vec3, Vec2) as 'registers' (I was thinking
like a CPU register), and controls the typed arrays underneath. It
automatically resizes them and provides a trim() function. While
resizing arrays is slow, it's still all way faster than millions of vec3
objects on a regular Geometry.

* Various Fixes

Fixed normal generation according to
https://www.opengl.org/wiki/Calculating_a_Surface_Normal
maybe various other cleanups.

* Revert "Various Fixes"

This reverts commit 4348a5f60b85ad8381e7ed3f19c0602a23bb87c4.

* Revert "Revert "Various Fixes""

This reverts commit c972529a2e0d869ac40d29409beb21420a833ad2.

* change the example to use BufferSubdivisionModifier

It's almost all working except for LatheGeometry. I'm not entirely sure
what is different about the lathegeometry , but I will investigate later
unless someone else figures it out first.

* change back to v2 and use phongmaterial

change back to v2 and use phongmaterial

* dispose of geometries

see title.

* Remove typedarray.slice's

in favor of typedarray.subarray's.

* slight cleanup to subarray

simply set the new buffers contents to the old buffers contents if
possible, otherwise use subarrays

* Tightened flattening of uniform array data.

* Updated builds.

* Fix levels property name

* correct type of levels array contents

* correct spacing of method parameters

* Move legacy code to Three.Legacy.js

[This commit](https://github.com/mrdoob/three.js/commit/0f5e69cec8a13d9b9819565f04b5db466548538d#diff-96b1bdbd7110f611907545802eaa5805R913)  changed a `url_array` to `urls` which broke the loader + example page. This patches SceneLoader to use the same naming convention in other files.

Normals weren't properly transformed in last exporter change so they were flipped on their sides 90 degrees. This fixes that issue so lighting works as expected. (#8647)

* ensure that an empty box is still an empty box aftering being transformed.

* fix docs to match new behavior.

- See #8446

* Documented Box3.applyMatrix4 doesn't work on empty boxes.

- See #8620

* Updated math Box classes' docs, style consistency.

Add high quality rand() function to common.glsl and an example to show off the noise textures. (#8603)

* create procedural glsl and an example to show off the noise textures.

* add to files.js

* adopt noise procedural in PMREMGenerator.

* fix page title per @arose's suggestion.

* more adoption of procedural.glsl

* remove procedural.glsl, add a single line to common.glsl.  Update other files as needed.

* cleanup shaders to use common.glsl

* tabify.

* avoid collapsing into a single function - @WestLangley recommendations

* more adoption of tabs.

* fix tabs.

sprite plugin: do not check texture.image, it allows to used textures created by RenderTarget (#8619)

* MatrixN: Deprecated .flattenToArrayOffset.

Instead .toArray consistently allows array and offset to be passed.

* Updated math classes' docs .toArray / .fromArray.

* Automated uniform.<name>.type.

* WebGLRenderer: Added .setTexture deprecation stub.

* Updated ShaderMaterial docs, uniform types.

* Updated Quaternion docs .toArray / .fromArray.

* Updated Quaternion docs, static .slerpFlat.

* Updated math classes' docs, style consistency.

* Updated ShaderMaterial docs, style consistency.

This helps when when the bounding box is not computed from an object, but comes from elsewhere

When Wrap Mode data is missing, fallback to Collada spec default repeated wrapping. Without this change the wrapping is clamped to edge which should not be the default behaviour.