Reveal trigger area during play

[SimonN]

Lix 0.9.40

Add a feature that reveals the trigger areas of exits, traps, ... during play.

It's not enough that you can go to the editor to check. This must be visible during play.

One idea is to merge this functionality with the splat ruler feature. Or make it a separate clear-physics mode, like in NeoLemmix. The problem with clear-physics mode is that it's hard to re-render the terrain in real-time with different colors.