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/AREngine.h

@@ -28,6 +28,7 @@ bool Init();
 void DeInit();
 void Reset();
 
+ARCodeFile* GetCodeFile();
 void SetCodeFile(ARCodeFile* file);
 
 void RunCheats();