[feature]-add-precision-flag-for-z

[eatyourpeas]

Thank you for creating this very useful package. Our use case at the Royal College of Paediatrics and Child Health in the UK involves calculating z scores from growth data to greater than 2 decimal places. Although nowhere is this requested on your issue page, might you consider reviewing/accepting this pull request to include this feature?

It adds a new optional parameter: z_precision where the user passes in the number of decimal places they require in the response (defaults to 2L if the flag is left empty). We have included some tests in your test suite for the new behaviour including tests in case users pass in negative value or non-integer values.

If you are happy with this we have also created a similar feature for anthroplus and are very happy to submit if you would consider reviewing that also.

[rkumapley]

Hi Simon,

Thank you for your contribution.
We are making some additional changes before integrating it into the package but your PR will be merged.
Can you please go ahead and make your contributions to the anthroplus as well

[dirkschumacher]

@eatyourpeas you have to run devtools::document() to update the docs under man/.

[eatyourpeas]

Many thanks @dirkschumacher. LMK if there is anything else you need.