Potential new materials

[Ealrann]

Bomb

Fall down, explode when touching something.

Acid

Same behaviour than lava, without fire ?
done: #18

Torch/Waterfall

We need the ability to put some static material. Two solutions:

• (bad) New specific materials (Torch/Waterfall)
• (good) Redraw the materials at the same place (Static materials could be drawn with shift-clic)
  => We need the capacity to make multiple draw every frames (Simply recall the compute shader?). No, impossible to remove it properly.
  => Tag the board with a static boolean?