cell iterator - add operator->

Implementation just forwards to operator*, but this is a typical operator in the iterator API and is suprising and inconvenient that it is not present

include/xlnt/worksheet/cell_iterator.hpp

@@ -96,6 +96,15 @@ public:
     /// </summary>
     const reference operator*() const;
 
+    /// <summary>
+    /// Dereferences this iterator to return the cell it points to.
+    /// </summary>
+    reference operator->();
+
+    /// <summary>
+    /// Dereferences this iterator to return the cell it points to.
+    /// </summary>
+    const reference operator->() const;
 
     /// <summary>
     /// Returns true if this iterator is equivalent to other.
@@ -222,7 +231,7 @@ public:
     /// <summary>
     /// Dereferences this iterator to return the cell it points to.
     /// </summary>
-    const cell operator*() const;
+    const reference operator->() const;
 
     /// <summary>
     /// Returns true if this iterator is equivalent to other.

source/worksheet/cell_iterator.cpp

@@ -279,4 +279,20 @@ const const_cell_iterator::reference const_cell_iterator::operator*() const
 {
     return ws_.cell(cursor_);
 }
+
+cell_iterator::reference cell_iterator::operator->()
+{
+    return operator*();
+}
+
+const cell_iterator::reference cell_iterator::operator->() const
+{
+    return operator*();
+}
+
+const const_cell_iterator::reference const_cell_iterator::operator->() const
+{
+    return operator*();
+}
+
 } // namespace xlnt