Pigs inside the CC on Deep Forest

[elexis]

The map Deep Forest places pigs near the civic center - sometimes inside the civic center.

Besides that the pigs can't be gathered from, units trying to reach them won't show up as idle.

Reproducible with the attached r20327 replay that can be started for alpha 22 as well (from command line or editing the version number).

[elexis]

Not so easy to solve.

The idea of Deep Forest is to be fancy and place entities using terrain painting rather than specific entity placement.

The city patch consists of three terrains. Pigs and chicken are part of the middle terrain. The LayeredPainter receives the outer width first, then the middle width and the inner width is the rest. This means we can't specify the inner width to ensure a minimum distance.

This means if the Terrain based entity placement approach is kept for the city patch, it will be either very easy to reintroduce that bug when only messing with the numbers, or we have to add code to remove entities again after having them placed already.

And that was only the consideration of the civic center. The pigs might just as well be stuck inside metal mines, which completely invalidates any radius-based testing.

So it's much safer to just place entities directly with avoidClasses constraints.

[elexis]

In 20906:

Fix pigs and chicken inside the CC and mines on Deep Forest by not using the terrain-painting based approach of placing entities which is free of any collision checks.
Fixes #4830.