Of water and stone

The transparent water looks much better. It still needs some improvements to look less blocky and flickery.
I also improved simulation to avoid over-acceleration on slopes. This is in preparation for water sounds (which would be wrong if water flowed too fast) and lava (which shouldn’t flow too fast). As the result, flows look much better now and vortices and other interesting effects have appeared.
I changed stone shader to make it easier to add new stones, and added some menhirs to mark magic circles.
Oh, and I added the main menu. I have logo designed on paper, but I didn’t get it into the game yet, so the title is just text for now.