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/Savestate.h

@@ -19,6 +19,7 @@
 #ifndef SAVESTATE_H
 #define SAVESTATE_H
 
+#include <string>
 #include <stdio.h>
 #include "types.h"
 
@@ -28,7 +29,7 @@
 class Savestate
 {
 public:
-    Savestate(const char* filename, bool save);
+    Savestate(std::string filename, bool save);
     ~Savestate();
 
     bool Error;