Typescript definitions file

[stefanfuchs]

I've made a simple typescript definitions file, I tested with the basic examples and it is working fine.
It might be worth adding it to the lib as the index.d.ts file:

declare module 'opus-media-recorder' {
  
  declare class OpusMediaRecorder extends MediaRecorder {
    constructor(stream: MediaStream, options?: MediaRecorderOptions, workerOptions?: OpusMediaRecorderWorkerOptions)
  }

  export interface OpusMediaRecorderWorkerOptions {
    encoderWorkerFactory: () => Worker,
    OggOpusEncoderWasmPath: string,
    WebMOpusEncoderWasmPath: string,
  }

  export = OpusMediaRecorder
}