Material props fillmode

[bnjm]

Implements support for material property fillMode: https://developer.apple.com/documentation/scenekit/scnfillmode?language=objc

[bnjm]

Currently works by setting the fillMode value to 0 or 1 i.e. material={{ fillMode: 0 }} corresponding to https://developer.apple.com/documentation/scenekit/scnfillmode/scnfillmodelines?language=objc

However even though it works it shows a failed prop type warning. I modelled this loosely on the already implemented blendMode implementation, which works like material={{ blendMode: 2 }}, but shows the same warning:

Maybe @macrozone knows what's going on here?

[bnjm]

Superseded by #115

Also re: propTypes warning, I was not declaring the props correctly, like material={{ blendMode: ARKit.BlendMode.Alpha }}