Function can_dig_up_stair

plugins/dig-now.cpp:262–266

}

static bool can_dig_up_stair(df::tiletype tt) {
    df::tiletype_shape shape = tileShape(tt);
    return shape == df::tiletype_shape::WALL ||
        shape == df::tiletype_shape::FORTIFICATION;
}

static bool can_dig_down_stair(df::tiletype tt) {
    df::tiletype_shape shape = tileShape(tt);