* Fix Matrix3 Matrix4 getInverse throwOnDegenerate

* Update throwOnDegenerate assertion

* Serialize and load JSON Light .shadow property

* Add .toJSON() method to LightShadow
* Light .toJSON() writes .shadow property
* Parse .shadow property in DirectionLight and Spotlight JSON data

* Remove .castShadow condition when exporting .shadow property to JSON

I’ve added a handful of improvements that I think will really help
people trying to use Maya with 3JS:

1. The current plugin will only perform an “EXPORT ALL” regardless of
what you select from the menu in Maya. I have fixed that so you can now
“Export All” or “Export Selected”. Export all sill merges geometry
rather than exporting a 3JS scene, may fix that in the future.
2. Updated the default extension to be “.json” rather than “.js”. This
is more in-line with 3JS and the other exporters.
3. I pulled the JSON encoder from the Blender exporter and integrated
it into the Maya one so that each item in the ups, faces, vertices, etc
arrays are no longer on a separate line. Makes the file MUCH easier to
read and debug.
4. Turned off sorting of the JSON output. This is more of an opinion,
but I didn’t feel like it helped the output at all.

* Simplify and enhance PropertyBinding Regex

* Update Regex of PropertyBinding.

* Update regular expression of PropertyBinding

* Clean up VREffect

* Remove the space after function name

First usage of `updateStyle` with now indication of what or where it came from.

* adds toJSON methods to scene and fog objects

* adds toJSON method to FogExp2

* adds fog instantiation to ObjectLoader.parse

* adds type info to fog JSON serialization and loading

* fixes unresolved conflict from rebase

* Adds THREE.UnsignedInt248Type and THREE.DepthStencilFormat constants

* Extends DepthTexture to allow for either THREE.DepthFormat or THREE.DepthStencilFormat

* Extends depthTexture initialization to support both DepthTextureFormat and DepthStencilFormat

* Fixes typos

* Ensures correct internal format for DepthStencil textures

* Allows to set depthTexture via options.depthTexture in constructor

* Fix method link 'ReturnType's of all math object documentation

* Misc Documentation fixes

* Add intersectSphere() method to Ray docs

* Remove ?s in Ray documentation after return values

These are unique phenomenon in the current docs and don't seem to
indicate anything meaningful.