collapse version 2.0.9

• Added functions na_locf() and na_focb() for fast basic C implementations of these procedures (optionally by reference). replace_na() now also has a type argument which supports options "locf" and "focb" (default "const"), similar to data.table::nafill. The implementation also supports character data and list-columns (NULL/empty elements). Thanks @BenoitLondon for suggesting (#489). I note that na_locf() exists in some other packages (such as imputeTS) where it is implemented in R and has additional options. Users should utilize the flexible namespace i.e. set_collapse(remove = "na_locf") to deal with this.

• Fixed a bug in weighted quantile estimation (fquantile()) that could lead to wrong/out-of-range estimates in some cases. Thanks @zander-prinsloo for reporting (#523).

• Improved right join such that join column names of x instead of y are preserved. This is more consistent with the other joins when join columns in x and y have different names.

• More fluent and safe interplay of 'mask' and 'remove' options in set_collapse(): it is now seamlessly possible to switch from any combination of 'mask' and 'remove' to any other combination without the need of setting them to NULL first.