Let BigDecimal#quo accept precision

[mrkn]

Fix GH-214.

[mrkn]

TODO:

• Support larger precision than the precision of the default result.

[olleolleolle]

To me, a casual reader, it looks good.

[mrkn]

What did you read? This PR isn't completed yet...

[olleolleolle]

@mrkn I read the carefully-worded documentation! :-)

[mrkn]

OK, I see. Thank you for checking the documentation part. But it needs to be modified after I will implement the longer precision support. Could you please check the update later.

By the way, the approval check only for the documentation part is noisy to me because the main topic of this PR is updating the logic of BigDecimal#quo. Could you please stop checking approval only for the documentation part to non-documentation PRs? Instead, it's easier to understand your intention that telling your opinion in comments at the documentation lines.

[mrkn]

@olleolleolle Could you check the documentation update?

[mrkn]

@olleolleolle I'll merge this. Please create a new PR to fix the documentation if you find some mistakes.

[olleolleolle]

(Reads perfectly, thanks!)