minor update manual

fix vehicle demo (heightfield is broken, when using very large scaling factor)
add btConeShape serialization, see Issue 725
add btGearConstraint get/set, see Issue 685 and Issue 671

src/BulletDynamics/ConstraintSolver/btGearConstraint.h

@@ -36,17 +36,48 @@ public:
 	///internal method used by the constraint solver, don't use them directly
 	virtual void getInfo1 (btConstraintInfo1* info);
 
-	///internal method used by the constraint solver, don't use them directly
-	virtual void getInfo2 (btConstraintInfo2* info);
-
-	virtual	void	setParam(int num, btScalar value, int axis = -1) 
+	///internal method used by the constraint solver, don't use them directly
+	virtual void getInfo2 (btConstraintInfo2* info);
+
+	void setAxisA(btVector3& axisA) 
 	{
-		btAssert(0);
-	};
+		m_axisInA = axisA;
+	}
+	void setAxisB(btVector3& axisB)
+	{
+		m_axisInB = axisB;
+	}
+	void setRatio(btScalar ratio)
+	{
+		m_ratio = ratio;
+	}
+	const btVector3& getAxisA() const
+	{
+		return m_axisInA;
+	}
+	const btVector3& getAxisB() const
+	{
+		return m_axisInB;
+	}
+	btScalar getRatio() const
+	{
+		return m_ratio;
+	}
+
+
+	virtual	void	setParam(int num, btScalar value, int axis = -1) 
+	{
+		(void) num;
+		(void) value;
+		(void) axis;
+		btAssert(0);
+	}
 
 	///return the local value of parameter
 	virtual	btScalar getParam(int num, int axis = -1) const 
 	{ 
+		(void) num;
+		(void) axis;
 		btAssert(0);
 		return 0.f;
 	}