v3.0.0

• Rewrite the project with TypeScript
• Fixes #43 and #39
• Update the API to export only these functions:
  • parse(input: string): Caption[]
  • stringify(captions: Caption[], options?: { format: 'srt' | 'vtt }): string
  • resync(captions: Caption[], time: number): Caption[]
  • parseTimestamp(timestamp: string): number
  • parseTimestamps(timestamps: string): Timestamp
  • formatTimestamp(timestamp: number, options?: { format: 'srt' | 'vtt' }): string
• parse supports optional indexes