Fuel State contract allows to commit to the same height more than once

[DefiCake]

I don't believe that you should be able to commit to the same height.

You commit once when you are ready. The challenge period is there. If it expires then you move on.
If someone invalidates then they should call some other function to clear the commit so that this function is usable again at that height.

Commentary is purely based on comment. I have not checked to see if this is already the case.

Originally posted by @Braqzen in #32 (comment)

[DefiCake]

Closed by #174