Added best times to challenge rooms.

After thinking about it, I decided to add the feature of best challenge room times being saved, only if you aren't using any assist options of course.

I came to the conclusion that it's better to have the feature there for those who enjoy it and assume that people that don't care about going fast will ignore it anyway.

I hope this doesn't make people assume I want them to rush anything, but only time will tell.

Have a nice day!