Method serialize

plugins/buildingplan/itemfilter.cpp:87–99

format: mat,mask,elements/materials,list/minq/maxq/decorated

// format: mat,mask,elements/materials,list/minq/maxq/decorated
string ItemFilter::serialize() const {
    std::ostringstream ser;
    ser << bitfield_to_string(mat_mask, ",") << "/";
    vector<string> matstrs;
    for (auto &mat : materials)
        matstrs.emplace_back(mat.getToken());
    ser << join_strings(",", matstrs);
    ser << "/" << static_cast<int>(min_quality);
    ser << "/" << static_cast<int>(max_quality);
    ser << "/" << static_cast<int>(decorated_only);
    ser << "/" << static_cast<int>(default_max_quality);
    return ser.str();
}

static void clampItemQuality(df::item_quality *quality) {
    if (*quality > df::item_quality::Artifact) {