Custom path support (#1333)

also including:
* getting rid of shitty strings
* all new, cleaner ROM handling code
* base for DSi savestates
* GBA slot addons (for now, memory cart)

src/frontend/qt_sdl/PathSettingsDialog.h

@@ -0,0 +1,67 @@
+
+/*
+    Copyright 2016-2021 Arisotura
+
+    This file is part of melonDS.
+
+    melonDS 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.
+
+    melonDS 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 melonDS. If not, see http://www.gnu.org/licenses/.
+*/
+
+#ifndef PATHSETTINGSDIALOG_H
+#define PATHSETTINGSDIALOG_H
+
+#include <QDialog>
+
+namespace Ui { class PathSettingsDialog; }
+class PathSettingsDialog;
+
+class PathSettingsDialog : public QDialog
+{
+    Q_OBJECT
+
+public:
+    explicit PathSettingsDialog(QWidget* parent);
+    ~PathSettingsDialog();
+
+    static PathSettingsDialog* currentDlg;
+    static PathSettingsDialog* openDlg(QWidget* parent)
+    {
+        if (currentDlg)
+        {
+            currentDlg->activateWindow();
+            return currentDlg;
+        }
+
+        currentDlg = new PathSettingsDialog(parent);
+        currentDlg->open();
+        return currentDlg;
+    }
+    static void closeDlg()
+    {
+        currentDlg = nullptr;
+    }
+
+    static bool needsReset;
+
+private slots:
+    void done(int r);
+
+    void on_btnSaveFileBrowse_clicked();
+    void on_btnSavestateBrowse_clicked();
+    void on_btnCheatFileBrowse_clicked();
+
+private:
+    Ui::PathSettingsDialog* ui;
+};
+
+#endif // PATHSETTINGSDIALOG_H