The `Vertices` link tool renders handles above all vertices of the link. It accepts three additional arguments, which can be passed as an object to the link tool constructor:

redundancyRemoval | boolean | If the user arranges three (or more) vertices so that they lie on a single line, should the middle one(s) be considered redundant and removed? Default is `true`. Note that this setting is not applied until the user actually moves one of the vertices in question; this means that vertices can still be arranged in this redundant fashion, using of the `link.vertices` function, for example.
snapRadius | number | While the user is moving the vertex, from how far away should the vertex snap in order to arrange itself perpendicularly to another vertex? Default is `20`.
vertexAdding | boolean | Can the user add new vertices (by clicking a segment of the link)? Default is `true`.
stopPropagation | boolean | Should be events stopped from propagating to the paper? Default is `true`.

Example:

    var verticesTool = new joint.linkTools.Vertices({
        focusOpacity: 0.5,
        redundancyRemoval: false,
        snapRadius: 10,
        vertexAdding: false,
    });