New RayCast class

That's all around b2Fixture::RayCast (b2RayCastOutput *output, const b2RayCastInput &input, int32 childIndex). QML/JS not allows to pass arguments by reference if I understand it right so I decided to push it to different object. It may be useful to get distance to nearest shape and whatever. I tried to keep names according to Box2D API. Also I created small exampe to test it

==========================================
Also I see my last commit after the pull request was included here so:
I've found that DebugDraw object was created each time step and it overloads CPU. I've changed it and maked some improvements:
- Added missed DrawTransform function (I taked Testbed as example)
- Added axis painting for circle to visualize rotation
- Added ability to select type of bodies for painting.
`debugShow: DebugDraw.Polygon |  DebugDraw.Circle`
- Added ability to set type of objects for painting.
`debugFlag: DebugDraw.ShapeBit|  DebugDraw.JointBit`
- Added ability to scale painted axes