(svn r10042) -Codechange: Replace hardcoded spritecache size with a configuration

option, sprite_cache_size. The default size is 2MB and the value can 
range from 1 to 64MB. If you experience slow-downs when scrolling the 
map, try increasing this setting.

src/spritecache.h

@@ -14,6 +14,8 @@ struct Sprite {
 	byte data[VARARRAY_SIZE];
 };
 
+extern uint _sprite_cache_size;
+
 const void *GetRawSprite(SpriteID sprite);
 bool SpriteExists(SpriteID sprite);