Chipmunk2D 7 Support

[jhasse]

Issues of Chipmunk2D which are blocking support for version 7 in Chipmunk++:

• cpPolyShapeNewRaw is not defined slembcke/Chipmunk2D#90
• Bring back cpRemoveCollisionHandler slembcke/Chipmunk2D#104
• No tag for Chipmunk 7 slembcke/Chipmunk2D#107

Last working version of Chipmunk++: https://github.com/jhasse/chipmunkpp/tree/v6.2.1

Stuff that needs to be figured out:

• Replacement for Shape::setGroup
• Replacement for Shape::setLayers

[jhasse]

Also created a 6.2.x branch now: https://github.com/jhasse/chipmunkpp/tree/6.2.x