- fix compilation issue on psp

- attempt at reducing loading times on the PSP: I merged a few graphics files together, removed some unused calls from the initialization functions, and moved some other ones to have a more lazy approach. The PSP version remains fairly slow in some parts (especially loading, but also entering the shop, or starting a new game), so I will try to reduce file access as much as possible in the days to come. Not a release blocker IMO though, but I4d sure love if it were faster.
- uppercased "Track1.mp3" to be in line with the actual filename. Most likely this had been broken forever on case-sensitive OSes
- I removed costly calls from the textscroller. I believe it wasn't very useful in its previous state. Now it's only "advertising" for unlockable stuff, which I think is ok (and allows to refresh it every time the menu is loaded)
- As a counterpart, added a "% complete" progress bar in the menu, something I wanted to add a while ago.

projects/mtg/include/AIPlayer.h

@@ -69,6 +69,7 @@ class AIPlayer: public Player{
 
 private:
     static int totalAIDecks; //a cache that counts the number of AI deck files in the AI folder. see getTotalAIDecks() below.
+    static int countTotalDecks(int lower, int higher, int current);
 
 protected:
     bool mFastTimerMode;