Removed fixed timestep logic from GameScreen (redundant now because the logic is handled in GameMain)

Subsurface/Source/Timing.cs

@@ -0,0 +1,40 @@
+using Microsoft.Xna.Framework;
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace Barotrauma
+{
+    static class Timing
+    {
+        private static double alpha;
+
+        public static double Accumulator;
+        public static double Step = 1.0 / 60.0;
+
+        public static double Alpha
+        {
+            get { return alpha; }
+            set { alpha = Math.Min(Math.Max(value, 0.0), 1.0); }
+        }
+
+        public static double Interpolate(double previous, double current)
+        {
+            return current * alpha + previous * (1.0 - alpha);
+        }
+
+        public static float Interpolate(float previous, float current)
+        {
+            return current * (float)alpha + previous * (1.0f - (float)alpha);
+        }
+
+        public static Vector2 Interpolate(Vector2 previous, Vector2 current)
+        {
+            return new Vector2(
+                Interpolate(previous.X, current.X),
+                Interpolate(previous.Y, current.Y));
+        }
+    }
+}