[crossfire] Weather bug

[Nicolas Weeger]

Hello.

There's a weather bug, seen on cat2.
Floor tiles disappear under 'rain<x>' archetypes.
Apparently it only happens when there is something apart the ground on
the tile (house, light, whatever).

I looked at the weather code, but can't right now find the issue.
Either the avoid_weather function, or something else -
singing_in_the_rain probably.

I'll try to look more in depth.

Ryo