0.6.3

[pwwang]

• ✨ 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
• 🐛 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
• ✨ Add datar.attrgetter(), datar.pd_str(), datar.pd_cat() and datar.pd_dt()