Refactor all examples:

fix #575, fix #604, fix #608, fix #634, fix #712

All examples are rewritten:

* Using Best Practices
* Mostly self-contained
* New examples to complete the feature matrix
* The server-framework example is removed

example/http/client/sync/CMakeLists.txt

@@ -0,0 +1,17 @@
+#
+# Copyright (c) 2016-2017 Vinnie Falco (vinnie dot falco at gmail dot com)
+#
+# Distributed under the Boost Software License, Version 1.0. (See accompanying
+# file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+#
+# Official repository: https://github.com/boostorg/beast
+#
+
+GroupSources(include/boost/beast beast)
+GroupSources(example/http/client/sync "/")
+
+add_executable (http-client-sync
+    ${BOOST_BEAST_INCLUDES}
+    Jamfile
+    http_client_sync.cpp
+)

example/http/client/sync/Jamfile

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+#
+# Copyright (c) 2016-2017 Vinnie Falco (vinnie dot falco at gmail dot com)
+#
+# Distributed under the Boost Software License, Version 1.0. (See accompanying
+# file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+#
+# Official repository: https://github.com/boostorg/beast
+#
+
+exe http-client-sync :
+    http_client_sync.cpp
+    :
+    <variant>coverage:<build>no
+    <variant>ubasan:<build>no
+    ;

example/http/client/sync/http_client_sync.cpp

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+//
+// Copyright (c) 2016-2017 Vinnie Falco (vinnie dot falco at gmail dot com)
+//
+// Distributed under the Boost Software License, Version 1.0. (See accompanying
+// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+//
+// Official repository: https://github.com/boostorg/beast
+//
+
+//------------------------------------------------------------------------------
+//
+// Example: HTTP client, synchronous
+//
+//------------------------------------------------------------------------------
+
+//[example_http_client
+
+#include <boost/beast/core.hpp>
+#include <boost/beast/http.hpp>
+#include <boost/beast/version.hpp>
+#include <boost/asio/connect.hpp>
+#include <boost/asio/ip/tcp.hpp>
+#include <cstdlib>
+#include <iostream>
+#include <string>
+
+using tcp = boost::asio::ip::tcp;       // from <boost/asio/ip/tcp.hpp>
+namespace http = boost::beast::http;    // from <boost/beast/http.hpp>
+
+// Performs an HTTP GET and prints the response
+int main(int argc, char** argv)
+{
+    try
+    {
+        // Check command line arguments.
+        if(argc != 4)
+        {
+            std::cerr <<
+                "Usage: http-client-sync <host> <port> <target>\n" <<
+                "Example:\n" <<
+                "    http-client-sync www.example.com 80 /\n";
+            return EXIT_FAILURE;
+        }
+        auto const host = argv[1];
+        auto const port = argv[2];
+        auto const target = argv[3];
+
+        // The io_service is required for all I/O
+        boost::asio::io_service ios;
+
+        // These objects perform our I/O
+        tcp::resolver resolver{ios};
+        tcp::socket socket{ios};
+
+        // Look up the domain name
+        auto const lookup = resolver.resolve({host, port});
+
+        // Make the connection on the IP address we get from a lookup
+        boost::asio::connect(socket, lookup);
+
+        // Set up an HTTP GET request message
+        http::request<http::string_body> req{http::verb::get, target, 11};
+        req.set(http::field::host, host);
+        req.set(http::field::user_agent, BOOST_BEAST_VERSION_STRING);
+
+        // Send the HTTP request to the remote host
+        http::write(socket, req);
+
+        // This buffer is used for reading and must be persisted
+        boost::beast::flat_buffer buffer;
+
+        // Declare a container to hold the response
+        http::response<http::dynamic_body> res;
+
+        // Receive the HTTP response
+        http::read(socket, buffer, res);
+
+        // Write the message to standard out
+        std::cout << res << std::endl;
+
+        // Gracefully close the socket
+        boost::system::error_code ec;
+        socket.shutdown(tcp::socket::shutdown_both, ec);
+
+        // not_connected happens sometimes
+        // so don't bother reporting it.
+        //
+        if(ec && ec != boost::system::errc::not_connected)
+            throw boost::system::system_error{ec};
+
+        // If we get here then the connection is closed gracefully
+    }
+    catch(std::exception const& e)
+    {
+        std::cerr << "Error: " << e.what() << std::endl;
+        return EXIT_FAILURE;
+    }
+    return EXIT_SUCCESS;
+}
+
+//]