Some minor fixes

[andreasnoack]

This should fix #1125 by handle levels and order arguments correctly in Scale. I've added some the examples from #1125 to ensure that this doesn't break again.

[codecov-io]

Codecov Report

Merging #1129 into master will increase coverage by 0.46%.
The diff coverage is 80.43%.

@@            Coverage Diff             @@
##           master    #1129      +/-   ##
==========================================
+ Coverage   86.09%   86.56%   +0.46%     
==========================================
  Files          32       32              
  Lines        3970     3959      -11     
==========================================
+ Hits         3418     3427       +9     
+ Misses        552      532      -20

Impacted Files	Coverage Δ
src/geometry.jl	71.42% <ø> (ø)	⬆️
src/aesthetics.jl	83.19% <100%> (+0.43%)	⬆️
src/scale.jl	89.28% <100%> (+7.53%)	⬆️
src/geom/ribbon.jl	100% <100%> (ø)	⬆️
src/geom/line.jl	90.21% <100%> (ø)	⬆️
src/geom/boxplot.jl	100% <100%> (ø)	⬆️
src/geom/beeswarm.jl	91.35% <100%> (ø)	⬆️
src/geom/errorbar.jl	97.29% <100%> (ø)	⬆️
src/geom/rectbin.jl	77.77% <100%> (ø)	⬆️
src/geom/polygon.jl	66.66% <100%> (ø)	⬆️
... and 7 more

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[tlnagy]

These are minor changes and they fix master so I think we should go ahead and merge.

[tlnagy]

Looks like RDatasets is dumping a bunch of deprecations due to JuliaData/CSV.jl#173. I have a fix for it at JuliaStats/RDatasets.jl#51