fix fence model to reduce draw calls about 3dstreet HOT 2 CLOSED

fence has 5 draw calls but is cloned like 100 times

• existing fence model: (5 draw calls, 1694 vertices 1412 triangles per each); 5 draw calls per fence * ~100 copies needed = ~500 draw calls
• found a new model, made it bigger, reduced draw calls (2 draw calls, 3376 vertices, 2942 triangles per each); now 2 draw calls per fence * ~16 copies needed = ~32 draw calls

from 3dstreet.

• before: 141200 triangles / 500 draw calls
• after: 47072 tris / 32 draw calls

from 3dstreet.