(devel/R-xfun) Updated 0.41 to 0.42

# CHANGES IN xfun VERSION 0.42

- `isFALSE()` has been fully deprecated for R >= 3.5.0, and will be
  completely removed from this package in the future
  (<https://yihui.org/en/2023/02/xfun-isfalse/>).

- Added a function `record()` to run R code and record the results,
  which is similar to `evaluate::evaluate()` but less sophisticated
  and technically simpler. One major difference is that
  `xfun::record()` records plots directly to files instead of saving
  them as display lists.

- `yaml_load()` gained an `envir` argument, which can be used to
  specify the environment to evaluate R expressions in YAML (i.e.,
  expressions written after `!expr` or `!r`). This is not
  straightforward in the upstream **yaml** package (thanks, @viking,
  vubiostat/r-yaml#54).

- `yaml_body()` gained the `...` argument to pass more arguments to
  `yaml_load()`.

- `split_source()` gained a `merge_comments` argument to merge
  consecutive lines of comments into the next code block, a
  `line_number` argument to store the line number of each expression
  in the returned value, and a `skip` argument to skip the rest of the
  code when the skip token is found.

- `check_old_package()` has been vectorized, i.e., the arguments
  `name` and `version` can take vectors now.

- Factored out the code for parsing chunk options and dividing a chunk
  into chunk options and chunk body from **knitr** to this package as
  functions `csv_options()` and `divide_chunk()`, respectively. They
  will be used by **knitr** and other packages in future.

- Added a function `decimal_dot()` to evaluate an expression after
  forcing `options(OutDec = '.')` and `Sys.setlocale(LC_NUMERIC =
  'C')` (for rstudio/rmarkdown#2525).


(mef)