Replaced std::tie with BlackMisc::tie, to help workaround tuples with more than 10 members.

This required some changes to the signatures of compare, qHash, and stream operators.
refs #182

src/blackmisc/tuple_private.h

@@ -20,6 +20,7 @@
 #include <QString>
 #include <tuple>
 #include <type_traits>
+#include <functional>
 
 namespace BlackMisc
 {
@@ -77,6 +78,29 @@ namespace BlackMisc
         }
         //! @}
 
+        // Helper which returns a copy of its argument if it's a tuple,
+        // otherwise returns a reference to its argument.
+        //! \private
+        //! @{
+        template <class T>
+        auto tieHelper(T &obj, std::false_type isTupleTag) -> std::reference_wrapper<T>
+        {
+            Q_UNUSED(isTupleTag);
+            return obj;
+        }
+        template <class T>
+        auto tieHelper(T &obj, std::true_type isTupleTag) -> T
+        {
+            Q_UNUSED(isTupleTag);
+            return obj;
+        }
+        template <class T>
+        auto tieHelper(T &obj) -> decltype(tieHelper(obj, IsTuple<T>()))
+        {
+            return tieHelper(obj, IsTuple<T>());
+        }
+        //! @}
+
 #ifdef Q_COMPILER_VARIADIC_TEMPLATES
 
         // Applying operations to all elements in a tuple, using recursion