Slides testing

I've been re-drawing the water slides directly on the "three rooms" test screen, because it feels easier to prototype there than within the reconstructed green zone level. Then I've been prototyping different things about it that I had in my notes ... only mostly ruling out some options so far. For instance, the idea of re-using the sprite of waterjets to avoid issues with waterfall-to-slide transition should be forgotten ... it helped me coding something to select the layer where Gobs should appear ... one of the things I'll need for the smashing fist.

Another such test was placing some special tiles along the slide, in an attempt to make them trigger some "fall and slide on slippery ground". 

That failed. Almost completely. I had to create an empty animation just to avoid the normal "special blocks handling" from deleting chunks of the slope as soon as Bilou touched them.

I also had to drop the idea of placing "jet" tiles in an attempt to push Bilou harder out of the slope at its bottom : they allowed (but only sometimes) Bilou to hover the whole slide upwards !