Account for Achievements and milk increases in efficiency calculations

[Riikka Kalliomäki]

Sometimes it's more efficient to buy certain number of buildings if that would give you an achievement and increase your milk. The efficiency should account for this fact when suggesting buildings or upgrades to buy.

[Riikka Kalliomäki]

Might implement this in the future. This will, however, require some major refactoring, so it is not an immediate goal.