Datar

- ✨ Allow `tidyr.unite()` to unite multiple columns into a list, instead of join them (105)
- 🩹 Fix typos in argument names of `tidyr.pivot_longer()` (104)
- 🐛 Fix `base.sprintf()` not working with Series (102)

- 🐛 Fix settingwithcopywarning in tidyr.pivot_wider()
- 📌 Pin deps for docs
- 💚 Don't upload coverage in PR
- 📝 Fix typos in docs (99, 100) (Thanks to pdwaggoner)

- ✨ Support `modin` as backend :kissing_heart:
- ✨ Add `_return` argument for `datar.options()`
- 🐛 Fix `tidyr.expand()` when `nesting(f.name)` as argument

Breaking changes

- 🩹 Make `base.ntile()` labels 1-based (92)

Fixes

- 🐛 Fix `order_by` argument for `dplyr.lead-lag`

Enhancements

- 🚑 Allow `base.paste/paste0()` to work with grouped data
- 🩹 Change dtypes of `base.letters/LETTERS/month_abb/month_name`

Housekeeping

- 📝 Update and fix reference maps
- 📝 Add `environment.yml` for binder to work
- 📝 Update styles for docs
- 📝 Update styles for API doc in notebooks
- 📝 Update README for new description about the project and add examples from StackOverflow

- ✨ Allow `base.c()` to handle groupby data
- 🚑 Allow `base.diff()` to work with groupby data
- ✨ Allow `forcats.fct_inorder()` to work with groupby data
- ✨ Allow `base.rep()`'s arguments `length` and `each` to work with grouped data
- ✨ Allow `base.c()` to work with grouped data
- ✨ Allow `base.paste()`/`base.paste0()` to work with grouped data
- 🐛 Force `&/|` operators to return boolean data
- 🚑 Fix `base.diff()` not keep empty groups
- 🐛 Fix recycling non-ordered grouped data
- 🩹 Fix `dplyr.count()/tally()`'s warning about the new name
- 🚑 Make `dplyr.n()` return groupoed data
- 🐛 Make `dplyr.slice()` work better with rows/indices from grouped data
- 🩹 Make `dplyr.ntile()` labels 1-based
- ✨ Add `datar.attrgetter()`, `datar.pd_str()`, `datar.pd_cat()` and `datar.pd_dt()`

- 🚑 Fix 87 boolean operator losing index
- 🚑 Fix false alarm from `rename()`/`relocate()` for missing grouping variables (89)
- ✨ Add `base.diff()`
- 📝 [doc] Update/Fix doc for case_when (87)
- 📝 [doc] Fix links in reference map
- 📝 [doc] Update docs for `dplyr.base`