add MultiDofDemo (Featherstone 3DOF spherical joint)

minor prettify of BasicDemo,RagdollDemo.
require 'multiDof' argument in btMultiBody.h (not default=false)

Demos3/bullet2/FeatherstoneMultiBodyDemo/MultiDofDemo.h

@@ -0,0 +1,34 @@
+
+#ifndef MULTI_DOF_DEMO_H
+#define MULTI_DOF_DEMO_H
+
+#include "BulletMultiBodyDemos.h"
+
+class MultiDofDemo : public FeatherstoneDemo1
+{
+	
+public:
+
+	MultiDofDemo(SimpleOpenGL3App* app);
+	virtual ~MultiDofDemo();
+
+
+	static BulletDemoInterface* MyCreateFunc(SimpleOpenGL3App* app)
+	{
+		return new MultiDofDemo(app);
+	}
+	
+	virtual void	initPhysics();
+
+	virtual void	stepSimulation(float deltaTime);
+
+
+	btMultiBody* createFeatherstoneMultiBody_testMultiDof(class btMultiBodyDynamicsWorld* world, int numLinks, const btVector3& basePosition, const btVector3 &baseHalfExtents, const btVector3 &linkHalfExtents, bool spherical = false, bool floating = false);
+	void addColliders_testMultiDof(btMultiBody *pMultiBody, btMultiBodyDynamicsWorld *pWorld, const btVector3 &baseHalfExtents, const btVector3 &linkHalfExtents);
+	void addBoxes_testMultiDof();
+
+
+};
+
+#endif //MULTI_DOF_DEMO_H
+