RMG: adjust the directory code in main.cpp

Source/RMG/main.cpp

@@ -11,8 +11,8 @@
 
 #include <QApplication>
 #include <QCommandLineParser>
-#include <QDir>
 #include <QFile>
+#include <QDir>
 
 #include <RMG-Core/Core.hpp>
 #include <iostream>
@@ -138,7 +138,15 @@ int main(int argc, char **argv)
     UserInterface::MainWindow window;
 
 #ifdef PORTABLE_INSTALL
-    QDir::setCurrent(app.applicationDirPath());
+    // we have to keep backwards compatability
+    // with <v0.5.2, so we'll check if a portable.txt file exists,
+    // or if the Config/mupen64plus.cfg file exists, if it does, 
+    // then change the current directory to the executable path
+    if (QFile(app.applicationDirPath() + "/portable.txt").exists() ||
+        QFile(app.applicationDirPath() + "/Config/mupen64plus.cfg").exists())
+    {
+        QDir::setCurrent(app.applicationDirPath());
+    }
 #endif
 
     QCoreApplication::setApplicationName("Rosalie's Mupen GUI");