sf CRS fixes

[ateucher]

Address #159:

• Don't access crs directly with attrs(), rather always use st_crs()
• Don't access crs slots with [[, rather use the $ methods.

[codecov-io]

Codecov Report

Merging #169 into master will increase coverage by 3.33%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master     #169      +/-   ##
==========================================
+ Coverage   51.44%   54.77%   +3.33%     
==========================================
  Files          30       30              
  Lines        1318     1318              
==========================================
+ Hits          678      722      +44     
+ Misses        640      596      -44     

Impacted Files	Coverage Δ
R/crs_convert.R	95.23% <100.00%> (+95.23%)	⬆️
R/zzz.r	58.19% <0.00%> (+0.40%)	⬆️
R/geojson_list.R	65.48% <0.00%> (+2.65%)	⬆️

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[sckott]

thanks @ateucher ! Does this work with the old sf version too?

[ateucher]

It should (by old you mean 0.8-1?)

[ateucher]

These github actions on mac are going to be the death of me

[sckott]

hmm, this one's failing https://github.com/ropensci/geojsonio/pull/169/checks?check_run_id=556636132 but i don't see a way to tell what version of sf it has

[sckott]

@ateucher getting lots of warnings on the crs_convert tests like

the following proj4string elements are ignored: +proj=longlat +datum=WGS84 +no_defs +ellps=WGS84 +towgs84=0,0,0 ; remove the +init=epsg:XXXX to undo this

[sckott]

Given that this change has some rough edges, i'm going to submit with these tests commented out

[ateucher]

I think that's a good idea, sorry I don't have a ton of time today to spend on it, but can try?

[sckott]

no worries, already submitted