Stop refreshing images cache when a game is selected

[Marcos González Troyas]

By default when entering a folder all the cache images that don’t exist or have expired are created, showing a progress bar on the top. On slow disks or network drives this is a hog, and when you select a different game, disk access for both actions must compete. Showing information about the game just selected should havehigher priority than cache refresh.

[Marcos González Troyas]

Seems it is not making the side bar slower to load, my fault.