Chipmunk2D 7 Support

[Jan Niklas Hasse]

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

• slembcke/Chipmunk2D#90
• slembcke/Chipmunk2D#104
• 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

[Jan Niklas Hasse]

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