Rounding options to toRelative

[Shiva127]

This PR fully address the issue described in #1129 (and fully replace PR #1683) by introducing an additional rounding option. This PR is fully backward compatible.

Problem

Before this PR, the only option for rounding with toRelative() is to rounds towards zero.

Solution

With this PR, I add a new parameter rounding who can be "towardsZero", "awayFromZero", "round", "floor", or "ceil" to address all options. The rounding option works with round: true and round: false.

I'm open for better names for "towardsZero", "awayFromZero".

Fixes #1129.

[hugohutri]

Nice! Good that you implemented the remaining rounding methods as well 😎
"towardsZero" and "awayFromZero" are pretty descriptive and I don't know if there are good alternatives. If we really want some other names for those, then "towardsZero" could be "truncate" or "clip" but awayFromZero is a bit harder to name imo 🤔 Maybe "expand" ?
But looks good anyway!

[Shiva127]

Nice! Good that you implemented the remaining rounding methods as well 😎

Thank you!

"towardsZero" and "awayFromZero" are pretty descriptive and I don't know if there are good alternatives.

Yes, it's descriptive but I don't know if there is a more accurate mathematical name for that.

If we really want some other names for those, then "towardsZero" could be "truncate" or "clip" but awayFromZero is a bit harder to name imo 🤔 Maybe "expand" ? But looks good anyway!

In this case I find "towardsZero" and "awayFromZero" more explicit than "truncate", "clip", or "expand".

[Shiva127]

I've found the rounding modes of Intl.NumberFormat() function and they use "expand" for "awayFromZero" and "trunc" for "towardsZero".

@hugohutri You were right. 😉