OutlineView drawing opacity fixes and style tweaks.

• Overrode UIView’s `clearsContextBeforeDrawing`, `opaque`, and `backgroundColor` getters in OutlineView to always return our dedicated values (`YES`, `NO`, and `nil` respectively).
	• initSuperOverrides method calls each super setter with our overridden getter to make sure everyone’s on the same page.
	• In Main.storyboard, changed OutlineView’s Background color, Opaque setting, and ClearsGraphics Context to the same values as the overrides.
• Now specifying the OutlineView’s lineColor (hot pink) and lineWidth (2pt) in the storyboard via User Defined Runtime Attributes.