add example loading heightfield from image and csv, using assets from DeepLoco (thanks to Jason Peng) and

from this Blender tutorial https://www.beamng.com/threads/tutorial-adding-heightmap-roads-using-blender.16356/

src/BulletCollision/CollisionShapes/btHeightfieldTerrainShape.h

@@ -185,6 +185,16 @@ public:
 	}
 	//debugging
 	virtual const char* getName() const { return "HEIGHTFIELD"; }
+
+	int m_userIndex2;
+	void setUserIndex2(int index)
+	{
+		m_userIndex2 = index;
+	}
+	int getUserIndex2() const
+	{
+		return m_userIndex2;
+	}
 };
 
 #endif  //BT_HEIGHTFIELD_TERRAIN_SHAPE_H