    util.breakText(text, size [, attrs, opt])

Break the `text` into lines so that the text fits into the bounding box defined by `size.width` and, optionally, `size.height`. `attrs` is an object with SVG attributes that will be set on the SVG text before measuring it (such as `font-weight`, `font`, ...). If `opt.svgDocument` is specified, that SVG document will be used to append the internally created SVG text element used for measurements (by default, an SVG document is created automatically for you). This function creates a temporary SVG <text> element with the attributes provided and continuously measures its width and height trying to fit as many words as possible on each line. When the text overflows the `size.height`, it is cut. The return value is a string with automatically added newline characters (\n) so that the text fits into the bounding box specified. Useful for implementing auto-wrapping of text in JointJS shapes.

    joint.util.breakText('this is quite a long text', { width: 50 })
    // 'this is\nquite a\nlong\ntext'