OBJLoader2 V2.2.0

- WorkerRunnerRefImpl changes: No longer required `THREE.LoaderSupport.Validator` and `THREE.LoaderSupport.ConsoleLogger` which reduces size of worker. Default workers only include WorkerRunnerRefImpl for establishing communication and no longer need the Validator or the ConsoleLogger.
- LoaderWorkerSupport changes: It always ensures logConfig parameters are properly initialized before being passed to worker. Fixed logging problems.
- Issue #25: OBJLoader2 now logs an error if `THREE.LoaderSupport` is not included as script in HTML. The same is true for missing `THRE.MTLLoader`, but only if method `loadMtl` is used.
- Issue #26: `WorkerSuport` now contains a inner private class `LoaderWorker` that encapsulates the native worker. This separates the runtime functionality from the setup and interaction. Workers are now terminated when immediately when they are not running otherwise `LoaderWorker.terminateRequested` ensures termination when final execution status is reached. `WorkerDirector` now properly handles shutdown of workers. Evaluation of status is always performed in `WorkerDirector.processQueue`. `WorkerDirector.callbackOnFinishedProcessing` is called when processing is completed and all workers are terminated. This allows to clear all meshes, for example.

ShapeUtils: Move triangulation code to separate file

ShapeUtils: Use earcut for polygon triangulation (2nd attempt)

FBXLoader refactor parseAnimation and remove unused entities from return object

GLTFLoader: Support sparse accessors.

Removed ImageUtils

Propagate error during loading of STL files via onError callback

TDSLoader: Use path and manager for all Loaders

FBXLoader support rotated pivots

FBXLoader correctly parse duplicate embedded textures

FBXLoader: refactor genGeo method

Fbx loader split monolithic parseScene method

ColladaLoader: Added possibility to manually set path

FBXLoader: parse layered textures

Update ImageLoader.html

GLTFExporter: Use utf-8 encoding for .glb JSON chunk.

Update Texture.html

ImageBitmapLoader: Added documentation