Reducing usage of #if CLIENT / #elif SERVER

The server will implement some classes it probably shouldn't need because certain items or game states depend on them.

BarotraumaShared/Source/Characters/AI/CrewCommander.cs

@@ -1,5 +1,4 @@
-#if CLIENT
-using Microsoft.Xna.Framework;
+using Microsoft.Xna.Framework;
 using Microsoft.Xna.Framework.Graphics;
 using System;
 using System.Linq;
@@ -312,4 +311,3 @@ namespace Barotrauma
         }
     }
 }
-#endif