Add utility AI (#806)

Co-authored-by: Pieter-Jan Briers <pieterjan.briers@gmail.com>
Co-authored-by: Metal Gear Sloth <metalgearsloth@gmail.com>
Co-authored-by: Pieter-Jan Briers <pieterjan.briers+git@gmail.com>

Content.Server/AI/Utility/Curves/LogisticCurve.cs

@@ -0,0 +1,28 @@
+using System;
+
+namespace Content.Server.AI.Utility.Curves
+{
+    public struct LogisticCurve : IResponseCurve
+    {
+        private readonly float _slope;
+
+        private readonly float _exponent;
+        // Vertical shift
+        private readonly float _yOffset;
+        // Horizontal shift
+        private readonly float _xOffset;
+
+        public LogisticCurve(float slope, float exponent, float yOffset, float xOffset)
+        {
+            _slope = slope;
+            _exponent = exponent;
+            _yOffset = yOffset;
+            _xOffset = xOffset;
+        }
+
+        public float GetResponse(float score)
+        {
+            return _exponent * (1 / (1 + (float) Math.Pow(Math.Log(1000) * _slope, -1 * score + _xOffset))) + _yOffset;
+        }
+    }
+}