modification of `webserver.cpp` example that shows how to use `url_obj`

webserver.cpp

#include <iostream>
#include <native/native.h>
#include <sstream>
using namespace native::http;

int main() {
    http server;
    int port = 8080;
    if(!server.listen("0.0.0.0", port, [](request& req, response& res) {
        res.set_status(200);
        res.set_header("Content-Type", "text/plain");

        auto url = req.url();
        std::stringstream ss;
        ss << "  req.url().schema(): " << url.schema() << '\n'
           << "    req.url().host(): " << url.host() << '\n'
           << "    req.url().port(): " << url.port() << '\n'
           << "    req.url().path(): " << url.path() << '\n'
           << "   req.url().query(): " << url.query() << '\n'
           << "req.url().fragment(): " << url.fragment() << "\n\n"
           << "Note that port() == 0 and fragment() == \"\"\n";

        if(url.path() == "/foo") {
            ss << "\nC++ FTW\n";
        }

        res.end(ss.str());
    })) return 1;

    std::cout << "Server running at http://0.0.0.0:" << port << "/" << std::endl;
    return native::run();
}