OutlineView path revision

• Changed OutlineView to generate its path ahead of time as a CGPathRef, and to intelligently recreate it (via a `setNeedsPathUpdate` method) when the points have changed, via a `setNeedsPathUpdate` method.
• Also using a `pointToScreenCoordTransform` CGAffineTransform in OutlineView to take over the point-coord › view-coord mapping.