Improve settler location AI

[ajhalme]

Basically just salvaging some ideas from #430 to improve the SettlerLocationAI with tile improvement metrics.

[ajhalme]

The more I read the SettlerLocationAI code, the less it seems like #430 has to add here.

Only thing that isn't really here is the potential food/production yield from a tile, but that's influenced by game rules on terrain improvement and player characteristics, etc. - an expensive calculation for not that much gain.

As such, I'm reducing this mainly to adding scaled contributions from the BFC outer ring to the existing tile scoring logic, as called for in #802.

Something like a quadratic penalty from distance could be an improvement over the current logic.

I believe this now closes #802. I don't think #430 has anything more to add either.

[stavrosfa]

Thanks, I only have one comment, as I wasn't really involved in any of this, so I can't really provide any usefull insight.

[stavrosfa]

Hmm, I have some reservations regarding this.

The BFC is not necessarily up to 2 tiles, as we have made this configurable in the rules

OpenCiv3/C7Engine/C7GameData/Rules.cs

Line 18 in 775869f

public int MaxRankOfWorkableTiles;

So I think it would be preferable if we added another method like

OpenCiv3/C7Engine/C7GameData/Tile.cs

Line 693 in 775869f

public List<Tile> GetTilesWithinRankDistance(int rank) {

excluding anything but the rank we want, to get the tiles

Unless this method is doing something extra which I am not immediatly getting.