Function starburst

starburst(
    outerRadius: number,
    points?: number,
    innerRadius?: number,
    origin?: Point,
    opts?: { initialAngleRadian?: number },
): readonly Point[]
Generates a starburst shape, returning an array of points. By default, initial point is top and horizontally-centred.
```
// Generate a starburst with four spikes
const pts = starburst(4, 100, 200);
```
points of two produces a lozenge shape. points of three produces a triangle shape. points of five is the familiar 'star' shape.

Note that the path will need to be closed back to the first point to enclose the shape.
Parameters
- outerRadius: number
  Outer radius. Maximum radius of a spike to origin
- points: number = 5
  Number of points in the starburst. Defaults to five, which produces a typical star
- OptionalinnerRadius: number
  Inner radius. A proportionally smaller inner radius makes for sharper spikes. If unspecified, 50% of the outer radius is used.
- origin: Point = PointEmpty
  Origin, or { x:0, y:0 } by default.
- Optionalopts: { initialAngleRadian?: number }
  Options
Returns readonly Point[]
Example: Create starburst and draw it. Note use of 'loop' flag to close the path
```
const points = starburst(4, 100, 200);
Drawing.connectedPoints(ctx, pts, {loop: true, fillStyle: `orange`, strokeStyle: `red`});
```
Options:
- initialAngleRadian: angle offset to begin from. This overrides the -Math.PI/2 default.
- Defined in geometry/src/shape/starburst.ts:34