Game & Demo Update v0.913

Hi adventurers,

v0.913 is now available on the game and demo branches:

• Fixed an issue when building a fortress wall on top of another one causing it to disappear

• Various optimizations

Let me know if you experience new instabilities with this version, as those optimizations required quite a few modifications. And in case of issues, don't hesitate to switch to the debug branch!

Thanks for playing, and please don't forget to leave a review, it helps a lot!