add the BT_ prefix for all #ifdef guards, to avoid conflicts with developers own header defines.

Fixes Issue 497

//license header
#ifndef BT_RIGIDBODY_H
#define BT_RIGIDBODY_H
class btRigidBody
{
};
#endif //BT_RIGIDBODY_H

src/BulletCollision/CollisionShapes/btConeShape.h

@@ -13,8 +13,8 @@ subject to the following restrictions:
 3. This notice may not be removed or altered from any source distribution.
 */
 
-#ifndef CONE_MINKOWSKI_H
-#define CONE_MINKOWSKI_H
+#ifndef BT_CONE_MINKOWSKI_H
+#define BT_CONE_MINKOWSKI_H
 
 #include "btConvexInternalShape.h"
 #include "BulletCollision/BroadphaseCollision/btBroadphaseProxy.h" // for the types
@@ -99,5 +99,5 @@ class btConeShapeZ : public btConeShape
 	public:
 		btConeShapeZ(btScalar radius,btScalar height);
 };
-#endif //CONE_MINKOWSKI_H
+#endif //BT_CONE_MINKOWSKI_H