Updated to MonoGame 3.6 + Directory refactor

- Barotrauma's projects are in the Barotrauma directory
- All libraries are in the Libraries directory
- MonoGame is now managed by NuGet, rather than referenced from the installed files (TODO: consider using PCL for easier cross-platform development?)
- NuGet libraries are not included in the repo, as getting the latest versions automatically should be preferred
- Removed Content/effects.mgfx as it didn't seem to be used anywhere
- Removed some references to Subsurface directory
- Renamed Launcher2 to Launcher

Barotrauma/BarotraumaShared/Source/GameSession/GameModes/MissionMode.cs

@@ -0,0 +1,26 @@
+using Microsoft.Xna.Framework;
+
+namespace Barotrauma
+{
+    partial class MissionMode : GameMode
+    {
+        private Mission mission;
+
+        public override Mission Mission
+        {
+            get
+            {
+                return mission;
+            }
+        }
+
+        public MissionMode(GameModePreset preset, object param)
+            : base(preset, param)
+        {
+            Location[] locations = { GameMain.GameSession.StartLocation, GameMain.GameSession.EndLocation };
+
+            MTRandom rand = new MTRandom(ToolBox.StringToInt(GameMain.NetLobbyScreen.LevelSeed));
+            mission = Mission.LoadRandom(locations, rand, param as string);
+        }
+    }
+}