`highlighting` - Configure which highlighter to use (and with which options) for each type of interaction.

##### List of highlighting interactions

- default - the default highlighter to use (and options) when none is specified
- connecting - when a valid link connection can be made to an element
- embedding - when a cell is dragged over another cell in embedding mode
- magnetAvailability - when showing all magnets to which a valid connection can be made
- elementAvailability - when showing all elements to which a valid connection can be made

Example usage:

    new joint.dia.Paper({
        highlighting: {
            'default': {
                name: 'stroke',
                options: {
                    padding: 3
                }
            },
            connecting: {
                name: 'addClass',
                options: {
                    className: 'highlight-connecting'
                }
            }
        }
    })