Improve Wire Rendering

[y.petremann]

As for now, wires are rendered as sprites that get transformed.
Because of this, wire strictly vertical and wire shadow strictly horizontal get 1 pixel wide and not antialiased :
- Wires can't be made thicker verticaly
- Wires hide when big poles are out of view but wire still goes in the view
- Wire gets ugly because no antialiasing is done on sprite transformation.

What I would propose is to render wire using shaders.
- It would make wire width consistent
- It doesn't need a perfect bezier curve, 32 point makes a good aproximation for a wire going from a pole to another.
- It doesn't need transformation antialias