Add support for linting example scripts

Docs: Added Scene.environment description.

CubeTexturePass: Fix usage of cube shader.

SubdivisionModifier: Fix runtime error with empty uvs.

Docs: Clean up.

GLTFLoader: Flip normalScale without tangents.

WebGLRenderer: Enable rendering of geometries with just an index.

Implemented Scene.environment

Editor: Move to ES6 modules (2nd attempt).

MeshSurfaceSampler: Accept Mesh as parameter, not BufferGeometry

Docs: Removed internal is* properties.

Describe limitation of point size

LightProbeHelper: Added doc page and TS file.

Add `internalFormat` to Texture

Docs: Added helpers in examples.

[GPUComputationRenderer] check if webgl2 is used before checking for extension OES_texture_float

Clean up.

Moved FaceNormalHelper, LightProbeHelper, PositionalAudioHelper, RectAreaLightHelper, VertexNormalsHelper and VertexTangentsHelper out of src