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/Content/BackgroundSprites/BackgroundCreaturePrefabs.xml

@@ -0,0 +1,22 @@
+<?xml version="1.0" encoding="utf-8" ?>
+<backgroundcreatures>
+  <Fish1 speed ="100.0" wanderamount="5.0" wanderzamount="0.1" swarmmin="2" swarmmax="10" swarmradius="500">
+    <Sprite texture="Content/BackgroundSprites/bgFish1.png" sourcerect="0,0,119,61"/>
+  </Fish1>
+
+  <Fish2 speed="40.0" wanderamount="0.2" wanderzamount="0.1" swarmmin="1" swarmmax="3" swarmradius="300">
+    <Sprite texture="Content/BackgroundSprites/bgFish1.png" sourcerect="1,65,113,64"/>
+  </Fish2>
+
+  <Fish3 speed="20.0" wanderamount="5.0" wanderzamount="0.1" swarmmin="3" swarmmax="6" swarmradius="300" disablerotation="true">
+    <Sprite texture="Content/BackgroundSprites/bgFish1.png" sourcerect="135,0,117,70"/>
+  </Fish3>
+
+  <Fish4 speed="200.0" wanderamount="5.0" wanderzamount="0.1" swarmmin="1" swarmmax="3" swarmradius="300">
+    <Sprite texture="Content/BackgroundSprites/bgFish1.png" sourcerect="117,70,139,64"/>
+  </Fish4>
+
+  <Fish5 speed="40.0" wanderamount="0.1" wanderzamount="0.1" swarmmin="1" swarmmax="3" swarmradius="300">
+    <Sprite texture="Content/BackgroundSprites/bgFish1.png" sourcerect="0,130,159,50"/>
+  </Fish5> 
+</backgroundcreatures>