`the_ground.js` update: * concrete wetness now goes from 0 to 4 (higher values "work" but are no
the_ground.js* concrete wetness now goes from 0 to 4 (higher values "work" but are not tested or intended)
- wetness spreads through the concrete
- spallation damage (from getting too how while wet) increases with wetness (and in practice, by how deep the water has gotten)
= absolutely catastrophic when this happens to concrete with wetness 4
* concrete is now damaged from freezing when wet, with damage increasing as the concrete is wetter
