Will also add Erin Catto's local implicit version from the GDC 2015 tutorial
Added demo for btGeneric6DofSpring2Constraint, thanks to Gabor Puhr
Add gfxBridge.autogenerateGraphicsObjects method for Bullet 2 demos in new framework (need to implement all Bullet 2 collision shape types...)
Use 1,1,1 for local scaling in btStaticPlaneShape
hinge->setParam(BT_CONSTRAINT_ERP,0.5);
btScalar erp = hinge->getParam(BT_CONSTRAINT_ERP);
Also, preliminary support for status bar messages in demo framework.
