getLandBasesSortieCost = () => {
        const total = {fuel: 0, ammo: 0, steel: 0, bauxite: 0};
        $.each(PlayerManager.bases, (i, base) => {
            if(base.action === 1) {
                var cost = base.calcSortieCost();
                Object.keys(total).map(k => { total[k] += cost[k]; });
            }
        });
        return total;
    }
@return total cost on sortie of all land bases set to sortie.
@see PlayerManager.bases
@see LandBase.calcSortieCost