disambiguated whether NodeParam::parent() would return a Node* or a QObject*

Old code assumes that a NodeParam's parent will always be a Node. The function
has been separated off and tweaked in the event that this is not the case.

app/node/inputarray.h

@@ -0,0 +1,11 @@
+#ifndef INPUTARRAY_H
+#define INPUTARRAY_H
+
+
+class InputArray
+{
+public:
+  InputArray();
+};
+
+#endif // INPUTARRAY_H