-Add: Debug level for cargo destinations.
-Codechange: Give towns and industries (as cargo producing and accepting entities) a common base class.
-Codechange: Store demand destinations for towns and industries.
-Codechange: Remove all demand links when deleting a town or industry.
-Codechange: Keep a bit mask of always accepted and produced cargos for industries.
-Feature: Display demand destinations in the town and industry detail windows.
-Feature: Clicking on a line in the demand destination list moves the viewport to the target.
-Add: A way to filter the candidates for getting a random town or industry by a callback function.
-Codechange: Helper functions to check if a town/industry accepts or supplies a cargo.
-Add: A basic, stupid demand link generator for towns and industries.
-Codechange: Keep a count of the incoming demand links for towns and industries.
-Codechange: Remove demand links when supply/acceptance changes.
-Change: Improve the demand link calculation for towns.
-Add: Demand link weight calculation for towns.
-Feature: Make sure all industries have at least one incoming demand link for each accepted cargo (if possible at all).
-Change: Improve the demand link generator for industries.
-Add: Demand link weight calculation for industries.