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/DSi_DSP.h

@@ -41,10 +41,10 @@ bool Init();
 void DeInit();
 void Reset();
 
-// TODO: needs to be called!
-// however, no DSi savestate stuff seems to be actually implemented?!
 void DoSavestate(Savestate* file);
 
+void DSPCatchUpU32(u32 _);
+
 // SCFG_RST bit0
 bool IsRstReleased();
 void SetRstLine(bool release);