Rename SpeedAdjustment -> MultiplierControlPoint + reworking.

osu.Game/Rulesets/Timing/MultiplierControlPoint.cs

@@ -0,0 +1,28 @@
+// Copyright (c) 2007-2017 ppy Pty Ltd <contact@ppy.sh>.
+// Licensed under the MIT Licence - https://raw.githubusercontent.com/ppy/osu/master/LICENCE
+
+using osu.Game.Beatmaps.ControlPoints;
+
+namespace osu.Game.Rulesets.Timing
+{
+    public class MultiplierControlPoint
+    {
+        /// <summary>
+        /// The time in milliseconds at which this control point starts.
+        /// </summary>
+        public readonly double StartTime;
+
+        /// <summary>
+        /// The multiplier which this control point provides.
+        /// </summary>
+        public double Multiplier => 1000 / TimingPoint.BeatLength / DifficultyPoint.SpeedMultiplier;
+
+        public TimingControlPoint TimingPoint = new TimingControlPoint();
+        public DifficultyControlPoint DifficultyPoint = new DifficultyControlPoint();
+
+        public MultiplierControlPoint(double startTime)
+        {
+            StartTime = startTime;
+        }
+    }
+}