Function normalise

normalise(ptOrX: number | Geometry.Point, y?: number): Geometry.Point
Normalise point as a unit vector.
```
normalise({x:10, y:20});
normalise(10, 20);
```
Parameters
- ptOrX: number | Geometry.Point
  Point, or x value
- Optionaly: number
  y value if first param is x
Returns Geometry.Point