make some code const correct.

src/BulletDynamics/Dynamics/btDynamicsWorld.h

@@ -135,6 +135,11 @@ public:
 			return m_solverInfo;
 		}
 
+		const btContactSolverInfo& getSolverInfo() const
+		{
+			return m_solverInfo;
+		}
+
 
 		///obsolete, use addAction instead.
 		virtual void	addVehicle(btActionInterface* vehicle) {(void)vehicle;}

src/BulletDynamics/Featherstone/btMultiBodyDynamicsWorld.h

@@ -72,6 +72,11 @@ public:
 		return m_multiBodies[mbIndex];
 	}
 
+	const btMultiBody*	getMultiBody(int mbIndex) const
+	{
+		return m_multiBodies[mbIndex];
+	}
+
 	virtual void	addMultiBodyConstraint( btMultiBodyConstraint* constraint);
 
 	virtual int     getNumMultiBodyConstraints() const