some 'const' specifications, putting the code to determine the default device

in its own file

devices.h

@@ -0,0 +1,13 @@
+#include <cstddef> // NULL
+
+class device {
+public:
+	device (const char * m_name, device * m_next = NULL) 
+	{
+		name = m_name; next = m_next;
+	}
+	const char * name;
+	device * next;
+};
+
+device * determine_default_device();