Add new interface that allows restarts

osu.Game/Rulesets/Mods/IApplicableForceRestart.cs

@@ -0,0 +1,16 @@
+// Copyright (c) 2007-2018 ppy Pty Ltd <contact@ppy.sh>.
+// Licensed under the MIT Licence - https://raw.githubusercontent.com/ppy/osu/master/LICENCE
+
+namespace osu.Game.Rulesets.Mods
+{
+    /// <summary>
+    /// Represents a mod which can override (and block) a fail.
+    /// </summary>
+    public interface IApplicableRestartOnFail : IApplicableMod
+    {
+        /// <summary>
+        /// Whether we allow restarting
+        /// </summary>
+        bool AllowRestart { get; }
+    }
+}