- 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/GameStateMenu.h

@@ -12,6 +12,7 @@ class GameStateMenu: public GameState, public JGuiListener
 private:
     TextScroller * scroller;
     int scrollerSet;
+    int mPercentComplete;
     JGuiController* mGuiController;
     SimpleMenu* subMenuController;
     SimpleMenu* gameTypeMenu;
@@ -50,6 +51,7 @@ private:
     string loadRandomWallpaper(); //loads a list of string of textures that can be randolmy shown on the loading screen
 
     void RenderTopMenu();
+    int gamePercentComplete();
 public:
 
     GameStateMenu(GameApp* parent);