Change Clone() to be const, which required constructors with const references and a const GetValue().

src/Dictionary.cpp

@@ -49,7 +49,7 @@ Dictionary::Dictionary(plist_t node, Node* parent) : Structure(parent)
     free(it);
 }
 
-Dictionary::Dictionary(PList::Dictionary& d) : Structure()
+Dictionary::Dictionary(const PList::Dictionary& d) : Structure()
 {
     for (Dictionary::iterator it = _map.begin(); it != _map.end(); it++)
     {
@@ -115,7 +115,7 @@ Dictionary::~Dictionary()
     _map.clear();
 }
 
-Node* Dictionary::Clone()
+Node* Dictionary::Clone() const
 {
     return new Dictionary(*this);
 }
@@ -140,7 +140,7 @@ Dictionary::iterator Dictionary::Find(const std::string& key)
     return _map.find(key);
 }
 
-Dictionary::iterator Dictionary::Set(const std::string& key, Node* node)
+Dictionary::iterator Dictionary::Set(const std::string& key, const Node* node)
 {
     if (node)
     {
@@ -154,6 +154,11 @@ Dictionary::iterator Dictionary::Set(const std::string& key, Node* node)
     return iterator(this->_map.end());
 }
 
+Dictionary::iterator Dictionary::Set(const std::string& key, const Node& node)
+{
+    return Set(key, &node);
+}
+
 Dictionary::iterator Dictionary::Insert(const std::string& key, Node* node)
 {
     return this->Set(key, node);