Implement basic virtual Room support based on enet (#2803)

* Added support for network with ENet lib,

connecting is possible, but data can't be sent, yet.

* fixup! Added support for network with ENet lib,

* fixup! CLang

* fixup! Added support for network with ENet lib,

* fixup! Added support for network with ENet lib,

* fixup! Clang format

* More fixups!

* Moved ENetHost* and ENetPeer* into pimpl classes

* fixup! Moved ENetHost* and ENetPeer* into pimpl classes

* fixup! Clang again

* fixup! Moved ENetHost* and ENetPeer* into pimpl classes

* fixup! Moved ENetHost* and ENetPeer* into pimpl classes

* fixup! Moved ENetHost* and ENetPeer* into pimpl classes

src/network/room_member.h

@@ -0,0 +1,65 @@
+// Copyright 2017 Citra Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#pragma once
+
+#include <atomic>
+#include <memory>
+#include <string>
+#include "common/common_types.h"
+#include "network/room.h"
+
+namespace Network {
+
+/**
+ * This is what a client [person joining a server] would use.
+ * It also has to be used if you host a game yourself (You'd create both, a Room and a
+ * RoomMembership for yourself)
+ */
+class RoomMember final {
+public:
+    enum class State : u8 {
+        Idle,    ///< Default state
+        Error,   ///< Some error [permissions to network device missing or something]
+        Joining, ///< The client is attempting to join a room.
+        Joined,  ///< The client is connected to the room and is ready to send/receive packets.
+        LostConnection, ///< Connection closed
+
+        // Reasons why connection was rejected
+        NameCollision,  ///< Somebody is already using this name
+        MacCollision,   ///< Somebody is already using that mac-address
+        CouldNotConnect ///< The room is not responding to a connection attempt
+    };
+
+    RoomMember();
+    ~RoomMember();
+
+    /**
+     * Returns the status of our connection to the room.
+     */
+    State GetState() const;
+
+    /**
+     * Returns whether we're connected to a server or not.
+     */
+    bool IsConnected() const;
+
+    /**
+     * Attempts to join a room at the specified address and port, using the specified nickname.
+     * This may fail if the username is already taken.
+     */
+    void Join(const std::string& nickname, const char* server_addr = "127.0.0.1",
+              const u16 serverPort = DefaultRoomPort, const u16 clientPort = 0);
+
+    /**
+     * Leaves the current room.
+     */
+    void Leave();
+
+private:
+    class RoomMemberImpl;
+    std::unique_ptr<RoomMemberImpl> room_member_impl;
+};
+
+} // namespace Network