dtplyr 1.0.0

• Converted from eager approach to lazy approach. You now must use lazy_dt()
  to begin a translation pipeline, and must use collect(), as.data.table(),
  as.data.frame(), or as_tibble() to finish the translation and actually
  perform the computation (#38).

  This represents a complete overhaul of the package replacing the eager
  evaluation used in the previous releases. This unfortunately breaks all
  existing code that used dtplyr, but frankly the previous version was
  extremely inefficient so offered little of data.table's impressive speed,
  and was used by very few people.

• dtplyr provides methods for data.tables that warning you that they use the
  data frame implementation and you should use lazy_dt() (#77)

• Joins now pass ... on to data.table's merge method (#41).

• ungroup() now copies it's input (@christophsax, #54).

• mutate() preserves grouping (@christophsax, #17).

• if_else() and coalesce() are mapped to data.table's fifelse() and
  fcoalesce() respectively (@MichaelChirico, #112)