- ifdef'd IPv6 tests

- fixed const-ness of stream() member functions to MemoryReader/Writer

Foundation/include/Poco/BinaryReader.h

@@ -200,7 +200,12 @@ public:
 		return _data;
 	}
 
-	MemoryInputStream& stream() const
+	const MemoryInputStream& stream() const
+	{
+		return _istr;
+	}
+
+	MemoryInputStream& stream()
 	{
 		return _istr;
 	}

Foundation/include/Poco/BinaryWriter.h

@@ -215,7 +215,12 @@ public:
 		return _data;
 	}
 
-	MemoryOutputStream& stream() const
+	const MemoryOutputStream& stream() const
+	{
+		return _ostr;
+	}
+
+	MemoryOutputStream& stream()
 	{
 		return _ostr;
 	}