    HighlighterView.add(cellView, selector, id, options)

Create an instance of the highlighter and add it to the cellView.

It returns an instance of the HighlighterView.

If a highlighter with the same id exists on the CellView, it is removed and a new highlighter is added and returned. You can check if a highlighter already exists by calling HighlighterView.get().

- cellView is an instance of dia.CellView.
- selector points to an SVGElement of the cellView. It must be one of the following types:

  Type | Description | Example
  --- | --- | ---

  String

  A selector from the cell's markup.

      'root'
      'body'

  Object

  An object with property selector, which is a selector from the (cell/label/port) markup.
  There is additional property port (id of a port) available for dia.ElementView.
  And property label (index of a label) is available for dia.LinkView.

  If no selector property is provided, the root is used.

      { selector: 'body' } // cells
      { port: 'port1', selector: 'portBody' } // elements
      { label: 1, selector: 'labelBody' } // links

  SVGElement

  An SVGElement, the descendant of cellView.el or the root itself.

      cellView.el // the root
      cellView.el.querySelector('rect') // an SVGRectangle

- id is a unique identifier of the highlighter. Only single highlighter with given id can exist on the CellView at one time.
- options passed to the constructor of the highlighter view.