Dark beasts - all southwest death tiles on which superiors cannot spawn

I've written an improvement for how we find a suitable tile to spawn on that should be in next week's release assuming it passes testing.

For more details, currently it checks the death tile of the slayer creature and some tiles around it. It will still prioritise doing this - but if it fails it will move on to checking the respawn tile of the dead creature and tiles around that. There is one more additional fallback.

It's not totally rigorous but I think now in almost all cases a successful tile should be found - we can make future tweaks if there are examples of superiors still having difficulty.

Thanks for the posts on it!

Lol, not this time I hope!