Contribution to add optional double precision floating point support. Define BT_USE_DOUBLE_PRECISION for all involved libraries/apps.

src/BulletCollision/CollisionShapes/btCompoundShape.h

@@ -85,11 +85,11 @@ public:
 	
 	virtual int	getShapeType() const { return COMPOUND_SHAPE_PROXYTYPE;}
 
-	virtual void	setMargin(float margin)
+	virtual void	setMargin(btScalar margin)
 	{
 		m_collisionMargin = margin;
 	}
-	virtual float	getMargin() const
+	virtual btScalar	getMargin() const
 	{
 		return m_collisionMargin;
 	}