Spreading Fire

With the improvements to fire in v0.49, I want to add more interactions with fire, so I experimented with an idea of fire spreading, but I think I may have gotten too carried away...

This can lead to additional ideas like Charcoal Makers having a chance to catch fire and having to be built away from other structures.

And then having certain buildings that can put out fire. (A player on Discord has mentioned something like a pump upgrade that can put out fire!)