add properties to get current past and future stack of HistoryStack

Pilz.Collections/SimpleHistory/SimpleHistory.vb

@@ -17,6 +17,26 @@ Namespace SimpleHistory
             End Get
         End Property
 
+        ''' <summary>
+        ''' Gets the current stack of all past HistoryPoints that are used for the Undo function.
+        ''' </summary>
+        ''' <returns></returns>
+        Public ReadOnly Property PastHistoryPoints As HistoryPoint()
+            Get
+                Return stackPast.ToArray
+            End Get
+        End Property
+
+        ''' <summary>
+        ''' Gets the current stack of all future HistoryPoints that are used for the Redo function.
+        ''' </summary>
+        ''' <returns></returns>
+        Public ReadOnly Property FutureHistoryPoints As HistoryPoint()
+            Get
+                Return stackFuture.ToArray
+            End Get
+        End Property
+
         ''' <summary>
         ''' Checks if the History has past changes.
         ''' </summary>