Inflate a surface by moving its control points up to a set of obstacles.

Input parameters:

1. Sf → Surface to inflate.
2. Ob → Obstacle shapes.
3. Lm → Optional inflation limit. If omitted, points that do not hit obstacles will not move at all.
4. Dr → Optional inflation direction. If omitted, the surface normal will be used.

Output parameters:

1. Sf → Inflated surface.