Highlight regions

Added regions option:

    regions: [
      {
        start: 0,
        end: 2,
        color: '#684c8a',
        title: 'Region 1',
        size: 20
      },
      {
        start: 6,
        end: 7,
        color: 'red',
        title: 'Region 2',
        size: 10
      }
    ]