message: relax tolerance for vertical slope
diff: @@ -297,7 +297,7 @@ namespace MakerJs.measure {
  */
  export function lineSlope(line: IPathLine): ISlope {
  var dx = line.end[0] - line.origin[0];
  - if (round(dx) == 0) {
  + if (round(dx, .000001) == 0) {
  return {
  line: line,
  hasSlope: false
  