Fix ceil and pow bug

[speeddragon]

This PR fix Ratio.ceil/1 bug when the remainder is 0 it doesn't increase by one, since the comparison is always false. I can remove this code since #99 fixes this also.

This also fixes Ratio.pow/2, when 0 is given, it returns 1 instead of 1 <|> 1.

[Qqwy]

Thank you very much!

I think it makes sense to keep the fix for Ratio.pow, and use the change to Ratio.ceil from PR #99.
So please remove that part of the code indeed 👍 .
EDIT: I prefer the approach of using rem as it probably is more readable (important) and it will also be a little faster (not super important but a little).

Great to see that you've add an extra example to the (doc)tests as well! Good work! 😄

[Qqwy]

😍 Version 3.0.1 which includes this PR has been published.

[speeddragon]

Thanks for the fast release.