Fix: Don't rely on static initialization to set up sprite font caches.

The order of static initialization is undefined, so this can cause initalization
before relevant caches are initializations.

src/fontcache.h

@@ -33,6 +33,8 @@ public:
 	FontCache(FontSize fs);
 	virtual ~FontCache();
 
+	static void InitializeFontCaches();
+
 	static int GetDefaultFontHeight(FontSize fs);
 
 	/**