Core/Movement: minor MotionMaster refactor

Source/Game/Entities/Unit/Unit.cs

@@ -181,6 +181,7 @@ namespace Game.Entities
 
             UpdateSplineMovement(diff);
             GetMotionMaster().UpdateMotion(diff);
+            UpdateUnderwaterState(GetMap(), GetPositionX(), GetPositionY(), GetPositionZ());
         }
         void _UpdateSpells(uint diff)
         {

Source/Game/Movement/MotionMaster.cs

@@ -81,15 +81,31 @@ namespace Game.Movement
             Contract.Assert(!empty());
 
             _cleanFlag |= MMCleanFlag.Update;
-            if (!top().Update(_owner, diff))
+            bool isMoveGenUpdateSuccess = top().Update(_owner, diff);
-            {
-                _cleanFlag &= ~MMCleanFlag.Update;
-                MovementExpired();
-            }
-            else
             _cleanFlag &= ~MMCleanFlag.Update;
 
+            if (!isMoveGenUpdateSuccess)
+                MovementExpired();
+
             if (_expireList != null)
+                ClearExpireList();
+        }
+
+        public void Clear(bool reset = true)
+        {
+            if (Convert.ToBoolean(_cleanFlag & MMCleanFlag.Update))
+            {
+                if (reset)
+                    _cleanFlag |= MMCleanFlag.Reset;
+                else
+                    _cleanFlag &= ~MMCleanFlag.Reset;
+                DelayedClean();
+            }
+            else
+                DirectClean(reset);
+        }
+
+        void ClearExpireList()
         {
             for (int i = 0; i < _expireList.Count; ++i)
             {
@@ -109,23 +125,6 @@ namespace Game.Movement
             _cleanFlag &= ~MMCleanFlag.Reset;
         }
 
-            _owner.UpdateUnderwaterState(_owner.GetMap(), _owner.GetPositionX(), _owner.GetPositionY(), _owner.GetPositionZ());
-        }
-
-        public void Clear(bool reset = true)
-        {
-            if (Convert.ToBoolean(_cleanFlag & MMCleanFlag.Update))
-            {
-                if (reset)
-                    _cleanFlag |= MMCleanFlag.Reset;
-                else
-                    _cleanFlag &= ~MMCleanFlag.Reset;
-                DelayedClean();
-            }
-            else
-                DirectClean(reset);
-        }
-
         public void MovementExpired(bool reset = true)
         {
             if (Convert.ToBoolean(_cleanFlag & MMCleanFlag.Update))