Make coord_sf() default use projected coords

[clauswilke]

Set default_crs = NULL, as discussed in #4494.

[clauswilke]

@thomasp85 Not entirely sure why this change happened. It doesn't seem to affect any of the reference images. If you think it matters, please let me know what I need to do to change this back. I updated to the latest vdiffr but that didn't seem to make a difference.

[thomasp85]

I think it is because you have an older version of freetypeharfbuzz installed and it records the version last used to validate the tests

[clauswilke]

I think this is done, but I'd like to do a bit more testing and review before committing to these changes.

[MikkoVihtakari]

One comment I can see just by skimming the diff: just default_crs = 4326 should be enough (the integer should be passed to st_crs() internally) as with the crs argument in previous versions of ggplot2. Now it says "default_crs = sf::st_crs(4326)" in the documentation.

[clauswilke]

Yes, default_crs = 4326 is sufficient. Just trying to be a bit more explicit and precise in the official documentation. For example, the datum argument has always been datum = sf::st_crs(4326).

[MikkoVihtakari]

Yep, I saw that now. It's in Usage though. Minor details, but perhaps just write in Details that both sf::st_crs(4326) and 4326 are sufficient and that 4326 will be passed to sf::st_crs?