Significantly slow down the fog and sky color transition effect

[IntegratedQuantum]

I slowed it down by 20× which makes it really hard to notice the transition (if it weren't for the color banding, but that's a different issue).
I looked around a bit, and I can only find one problem: if you move out of a cave too fast the sky is grey (depending on what cave you come from), but I think that shouldn't be too noticable in survival.

fixes #2096

@ikabod-kee please check if this is good.

[ikabod-kee]

Okay, first thing I tested with this implementation is dying in a cave. Now when you respawn on the surface, it takes way too long for the fog to transition. This can be fixed really easily with a band-aid, but consider my method instead: fog averaging based on distance from biome borders.

[IntegratedQuantum]

but consider my method instead: fog averaging based on distance from biome borders

I think that would be problematic when falling, e.g. if you fall down the root hole, then you would see fog alternate every couple seconds.
Same goes for all future fast surface travel.

[ikabod-kee]

but consider my method instead: fog averaging based on distance from biome borders

I think that would be problematic when falling, e.g. if you fall down the root hole, then you would see fog alternate every couple seconds. Same goes for all future fast surface travel.

You could dynamically sample it based on the player's speed?

[ikabod-kee]

Or make the fade-rate lower as you go faster??

[IntegratedQuantum]

You could dynamically sample it based on the player's speed?

How would that work, do you mean implementing both time based and position based averaging? I'd rather avoid having such a complex system for determining fog.