Made Property::encodeAttribute static.

src/App/Property.cpp

@@ -114,7 +114,7 @@ void Property::Paste(const Property& /*from*/)
     assert(0);
 }
 
-std::string Property::encodeAttribute(const std::string& str) const
+std::string Property::encodeAttribute(const std::string& str)
 {
     std::string tmp;
     for (std::string::const_iterator it = str.begin(); it != str.end(); ++it) {

src/App/Property.h

@@ -96,7 +96,7 @@ public:
     /// Paste the value from the property (mainly for Undo/Redo and transactions)
     virtual void Paste(const Property &from) = 0;
     /// Encodes an attribute upon saving.
-    std::string encodeAttribute(const std::string&) const;
+    static std::string encodeAttribute(const std::string&);
 
 
     friend class PropertyContainer;