[experimental] standardize function arguments

[JanMarvin]

library(openxlsx2)

xlsxFile <- system.file("extdata", "openxlsx2_example.xlsx", package = "openxlsx2")
wb1 <- wb_load(xlsxFile)

# camelCase from the example
wb_to_df(wb1, sheet = 2, dims = "C6:G9", rowNames = TRUE)
#>                mpg cyl disp  hp
#> Mazda RX4     21.0   6  160 110
#> Mazda RX4 Wag 21.0   6  160 110
#> Datsun 710    22.8   4  108  93

# snake_case
wb_to_df(wb1, sheet = 2, dims = "C6:G9", row_names = TRUE)
#>                mpg cyl disp  hp
#> Mazda RX4     21.0   6  160 110
#> Mazda RX4 Wag 21.0   6  160 110
#> Datsun 710    22.8   4  108  93

I have squashed in many changes. Most functions should accept snake_case and camelCase arguments.

ToDo in follow up commits

• Examples still need updates
• Check for unused arguments
• See how much code is broken
• Further updates for NEWs
• I've marked this experimental. If it breaks to much, it will have to be reverted

[olivroy]

Hi @JanMarvin, as I mentioned in the related issue (#38 (comment)), I think it would be good to phase out xlsxFile (xlsx_file) for just file for consistency throughout!

Edit: for clarity, the error message when file is not xlsx,
Error in f()
x file must be an xlsx file.