Initial CEF and DirectX overlay implementation (PoC, unfinished)

Still pretty unstable, game might crash at times.
Revamp build system and other small fixes

Client/Scripts/GUI/CefManager.cs

@@ -0,0 +1,121 @@
+using System;
+using System.Collections.Concurrent;
+using System.Collections.Generic;
+using System.Drawing;
+using System.Windows.Forms;
+using DXHook.Hook.Common;
+using GTA;
+using GTA.Native;
+using RageCoop.Client.CefHost;
+using RageCoop.Client.Scripting;
+using RageCoop.Core;
+
+namespace RageCoop.Client.GUI
+{
+    internal static class CefManager
+    {
+        private static readonly ConcurrentDictionary<int, CefClient> Clients =
+            new ConcurrentDictionary<int, CefClient>();
+
+        private static readonly Overlay CefOverlay = new Overlay
+        {
+            Elements = new List<IOverlayElement>(),
+            Hidden = false
+        };
+
+        static CefManager()
+        {
+            Main.CefRunning = true;
+            HookManager.Initialize();
+            CefController.Initialize(@"RageCoop\SubProcess\RageCoop.Client.CefHost.exe");
+            CefController.OnCefMessage = m => API.Logger.Debug(m);
+            HookManager.AddOverLay(CefOverlay);
+        }
+
+        public static CefClient ActiveClient { get; set; }
+
+        public static void Test()
+        {
+            var c = CreateClient(new Size(640, 480));
+            c.Scale = 0.8f;
+            c.Opacity = 128;
+            Script.Wait(2000);
+            c.Controller.LoadUrl("https://ragecoop.online/");
+            ActiveClient = c;
+        }
+
+        public static void Tick()
+        {
+            if (ActiveClient != null)
+            {
+                Game.DisableAllControlsThisFrame();
+                Function.Call(Hash._SET_MOUSE_CURSOR_ACTIVE_THIS_FRAME);
+                ActiveClient.Tick();
+            }
+        }
+
+        public static void KeyDown(Keys key)
+        {
+        }
+
+        public static void KeyUp(Keys key)
+        {
+        }
+
+        public static bool DestroyClient(CefClient client)
+        {
+            lock (Clients)
+            {
+                if (Clients.TryRemove(client.Id, out var c) && client == c)
+                {
+                    client.Destroy();
+                    CefOverlay.Elements.Remove(client.MainFrame);
+                    if (ActiveClient == client) ActiveClient = null;
+                    return true;
+                }
+            }
+
+            return false;
+        }
+
+        public static CefClient CreateClient(Size size)
+        {
+            lock (Clients)
+            {
+                var id = 0;
+                while (id == 0 || Clients.ContainsKey(id)) id = CoreUtils.RandInt(0, int.MaxValue);
+                var client = new CefClient(id, size);
+                if (Clients.TryAdd(id, client))
+                {
+                    CefOverlay.Elements.Add(client.MainFrame);
+                    return client;
+                }
+
+                API.Logger.Warning("Failed to create CefClient");
+                client.Destroy();
+                return null;
+            }
+        }
+
+        public static void CleanUp()
+        {
+            Main.CefRunning = false;
+            ActiveClient = null;
+            try
+            {
+                lock (Clients)
+                {
+                    foreach (var c in Clients.Values) DestroyClient(c);
+
+                    Clients.Clear();
+                }
+
+                CefController.ShutDown();
+            }
+            catch (Exception ex)
+            {
+                API.Logger.Error(ex);
+            }
+        }
+    }
+}