Add FatalErrorHandler

Allows us to display a message to the user and quit when an
unrecoverable error occurs.

Can't really be tested unfortunately.

ModuleManager/FatalErrorHandler.cs

@@ -0,0 +1,38 @@
+using System;
+using UnityEngine;
+
+namespace ModuleManager
+{
+    public static class FatalErrorHandler
+    {
+        public static void HandleFatalError(string message)
+        {
+            try
+            {
+                PopupDialog.SpawnPopupDialog(new Vector2(0.5f, 0.5f),
+                    new Vector2(0.5f, 0.5f),
+                    new MultiOptionDialog(
+                        "ModuleManagerFatalError",
+                        $"ModuleManager has encountered a fatal error and KSP needs to close.\n\n{message}\n\nPlease see KSP's log for addtional details",
+                        "ModuleManager - Fatal Error",
+                        HighLogic.UISkin,
+                        new Rect(0.5f, 0.5f, 500f, 60f),
+                        new DialogGUIFlexibleSpace(),
+                        new DialogGUIHorizontalLayout(
+                            new DialogGUIFlexibleSpace(),
+                            new DialogGUIButton("Quit", Application.Quit, 140.0f, 30.0f, true),
+                            new DialogGUIFlexibleSpace()
+                        )
+                    ),
+                    true,
+                    HighLogic.UISkin);
+            }
+            catch(Exception ex)
+            {
+                Debug.LogError("Exception while trying to create the fatal exception dialog");
+                Debug.LogException(ex);
+                Application.Quit();
+            }
+        }
+    }
+}

ModuleManager/ModuleManager.csproj

@@ -44,6 +44,7 @@
     <Compile Include="Extensions\StringExtensions.cs" />
     <Compile Include="Extensions\UrlConfigExtensions.cs" />
     <Compile Include="IPatchProgress.cs" />
+    <Compile Include="FatalErrorHandler.cs" />
     <Compile Include="Logging\ExceptionMessage.cs" />
     <Compile Include="Logging\IBasicLogger.cs" />
     <Compile Include="Logging\ILogMessage.cs" />