implement entire project in nodes

Project items are now represented directly in nodes opening up more versatility and possibilities. This is the first iteration of this and will be buggy. Need to test thoroughly.

app/dialog/configbase/configdialogbasetab.h

@@ -0,0 +1,43 @@
+/***
+
+  Olive - Non-Linear Video Editor
+  Copyright (C) 2020 Olive Team
+
+  This program is free software: you can redistribute it and/or modify
+  it under the terms of the GNU General Public License as published by
+  the Free Software Foundation, either version 3 of the License, or
+  (at your option) any later version.
+
+  This program is distributed in the hope that it will be useful,
+  but WITHOUT ANY WARRANTY; without even the implied warranty of
+  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+  GNU General Public License for more details.
+
+  You should have received a copy of the GNU General Public License
+  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+***/
+
+#ifndef PREFERENCESTAB_H
+#define PREFERENCESTAB_H
+
+#include <QWidget>
+
+#include "config/config.h"
+#include "undo/undocommand.h"
+
+namespace olive {
+
+class ConfigDialogBaseTab : public QWidget
+{
+public:
+  ConfigDialogBaseTab() = default;
+
+  virtual bool Validate();
+
+  virtual void Accept(MultiUndoCommand *parent) = 0;
+};
+
+}
+
+#endif // PREFERENCESTAB_H