Automatically redownload beatmaps that failed to load

[Cyliann]

If an error "Beatmap failed to load (file not found on disk)" occurs or beatmap is corrupted in any other way, osu should:

1. try to automatically redownload said beatmap to fix the problem or
2. have an option to manually redownload said beatmap

I think it shouldn't be hard to implement since the "beatmap update" functionality is already there.

[Cyliann]

As developers now have more time to look into user's requests, could someone take another look at this proposal?

Now the only way to fix a corrupted beatmap is to remove it (potentially loosing the scores; it happened to me a few times) and download it manually.