Introduced the MasterController as part of working on loading catalogue information.

Need a central piece to manage the catalogue data per database to prevent loading
this multiple times. MasterController is now also used to enable reopening the
connection manager from a query window after the connection manager has been closed.

paramtypedelegate.h

@@ -0,0 +1,25 @@
+#ifndef PARAMTYPEDELEGATE_H
+#define PARAMTYPEDELEGATE_H
+
+#include <QStyledItemDelegate>
+
+class TypeSelectionItemModel;
+
+/** Item delegate for supplying a combobox for selected the parameter type in
+ * the parameter list.
+ */
+class ParamTypeDelegate : public QStyledItemDelegate
+{
+	Q_OBJECT
+public:
+	ParamTypeDelegate();
+	~ParamTypeDelegate();
+
+	QWidget *createEditor(QWidget *parent, const QStyleOptionViewItem &option,
+							  const QModelIndex &index) const override;
+
+private:
+	TypeSelectionItemModel* m_typeSelectionModel = nullptr;
+};
+
+#endif // PARAMTYPEDELEGATE_H