round to six decimal places

[jgravois]

alternative to #52

• round instead of truncate, for slightly more accurate results
• yanked const/let in favor of good ol 'var'
  this codebase is old as hell. its due for a facelift, but i'd rather let (groan!) sleeping dogs lie for now.
• added WKT tests to confirm those values are rounded too
• updated doc

does this seem reasonable @KD33?

ps: i would have just pushed to the PR that was already open, but you either unticked the box or the option was disabled because you're PRing directly from your own main branch

[KD33]

Looks good to me. Thanks a lot!

[jgravois]

@springmeyer in #49 i suggested you make main a protected branch without realizing that one of the default rules prohibits non-admins like me from merging PRs without code review 🤦‍♂️

at this point you have two options:

1. untick the box below if you'd like me to be able to take small stuff like this coast to coast on my own
2. if you'd rather I not go rogue, you can continue to approve PRs individually

i'm happy either way, and will seek feedback regardless if i ever decide to pitch something substantive.

[springmeyer]

@jgravois I've unchecked the box requiring approvals to make sure you are not blocked from merging small stuff. Thanks!