Feature/httpd (#94)

* Stub code for http server

* can send a response, cannot process body yet

* write headers to the response

* remove commented code

* add simple test + set default http handler

* tweak CI + unittest

* add missing file

* rewrite http::trim in a simple way

* doc

test/IXHttpServerTest.cpp

@@ -0,0 +1,70 @@
+/*
+ *  IXSocketTest.cpp
+ *  Author: Benjamin Sergeant
+ *  Copyright (c) 2019 Machine Zone. All rights reserved.
+ */
+
+#include <iostream>
+#include <ixwebsocket/IXHttpClient.h>
+#include <ixwebsocket/IXHttpServer.h>
+#include "IXGetFreePort.h"
+
+#include "catch.hpp"
+
+using namespace ix;
+
+TEST_CASE("http server", "[httpd]")
+{
+    SECTION("Connect to a local HTTP server")
+    {
+        int port = getFreePort();
+        ix::HttpServer server(port, "127.0.0.1");
+
+        auto res = server.listen();
+        REQUIRE(res.first);
+        server.start();
+
+        HttpClient httpClient;
+        WebSocketHttpHeaders headers;
+
+        std::string url("http://127.0.0.1:");
+        url += std::to_string(port);
+        url += "/data/foo.txt";
+        auto args = httpClient.createRequest(url);
+
+        args->extraHeaders = headers;
+        args->connectTimeout = 60;
+        args->transferTimeout = 60;
+        args->followRedirects = true;
+        args->maxRedirects = 10;
+        args->verbose = true;
+        args->compress = true;
+        args->logger = [](const std::string& msg)
+        {
+            std::cout << msg;
+        };
+        args->onProgressCallback = [](int current, int total) -> bool
+        {
+            std::cerr << "\r" << "Downloaded "
+                      << current << " bytes out of " << total;
+            return true;
+        };
+
+        auto response = httpClient.get(url, args);
+
+        for (auto it : response->headers)
+        {
+            std::cerr << it.first << ": " << it.second << std::endl;
+        }
+
+        std::cerr << "Upload size: " << response->uploadSize << std::endl;
+        std::cerr << "Download size: " << response->downloadSize << std::endl;
+        std::cerr << "Status: " << response->statusCode << std::endl;
+        std::cerr << "Error message: " << response->errorMsg << std::endl;
+
+        REQUIRE(response->errorCode == HttpErrorCode::Ok);
+        REQUIRE(response->statusCode == 200);
+
+        server.stop();
+    }
+}