/**
	 * Given the current selected Company slot and a direction to search,
	 * get the first free Company slot that is found.
	 * @note Returns INVALID_COMPANY if none was found.
	 * @note A direction must be provided.
	 * @param slot The currently selected Company slot
	 * @param dir The direction to search (-1 to search above, +1 to search below)
	 * @pre (dir == -1 || dir == +1)
	 * @return the first free CompanyID that is found from the given direction
	 */
	static CompanyID GetFreeSlot(CompanyID slot, int dir = 0)
	{
		assert(dir == -1 || dir == +1);
		if (dir == -1) {
			slot--;
			for (slot; slot >= COMPANY_FIRST; slot--) {
				if (IsConsideredDead(slot)) return slot;
			}
		} else {
			if (dir == +1) {
				slot++;
				for (slot; slot < MAX_COMPANIES; slot++) {
					if (IsConsideredDead(slot)) return slot;
				}
			}
		}
		return slot = INVALID_COMPANY;
	}