Improve biter egg spoiling behavior when carried by robot flying over non-survivable terrain

[h.q.droid]

While doing an egg setup overhaul, I had 10k+ eggs spoiling at the same time which overwhelmed my bot-based biter burner. The resulting biters formed dense lines along robot routes.

The problem is, quite a lot of them ended up spawned inside deep ocean. They survived and just sat on top of the water like some kind of biter Moses. It was hilarious but also felt weird since biters don't normally do that and the looks are off.

I suggest either wait for the robot to reach feasible terrain before spawning the biter, or kill the biters with some biter-fell-into-water-and-drown animation

[eugenekay]

Yup, that is Not a Bug - it's just a floating Bug!

I don't think there are any "Good" ways to handle this case for Eggs:

• Delaying Spoilage until the Egg reaches land is probably unfeasible due to the way in which Ticks-to-Spoil is implemented internally the Item has no idea where it is - it just happens when the counter hits 0.
• Scanning the Map to find the Nearest Land Tile is probably a bad idea due to the expense of performing a "Scan" for the nearest valid Tile across potentially Thousands of items in a Tick.
• Voiding the result (drowning the Biter) completely undermines the intentional Danger of Egg Handling.

I think a better idea would be to just let Biters who are already on a Water tile to walk onto adjacent Water tiles. Then they would "naturally" walk towards Land.