override Scene.cpp; Move common menu/scene to new file; Cleanup

Closes #50

Signed-off-by: falkTX <falktx@falktx.com>

src/CardinalCommon.hpp

@@ -0,0 +1,32 @@
+/*
+ * DISTRHO Cardinal Plugin
+ * Copyright (C) 2021 Filipe Coelho <falktx@falktx.com>
+ *
+ * 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 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.
+ *
+ * For a full copy of the GNU General Public License see the LICENSE file.
+ */
+
+#include <string>
+
+#pragma once
+
+namespace patchUtils
+{
+
+void loadDialog();
+void loadPathDialog(const std::string& path);
+void loadTemplateDialog();
+void revertDialog();
+void saveDialog(const std::string& path);
+void saveAsDialog();
+
+}