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

Libraries/Lidgren.Network/NetStoredReliableMessage.cs

@@ -0,0 +1,19 @@
+using System;
+
+namespace Lidgren.Network
+{
+	internal struct NetStoredReliableMessage
+	{
+		public int NumSent;
+		public double LastSent;
+		public NetOutgoingMessage Message;
+		public int SequenceNumber;
+
+		public void Reset()
+		{
+			NumSent = 0;
+			LastSent = 0.0;
+			Message = null;
+		}
+	}
+}