add quality test using Aqua

[t-bltg]

• drop Contour, LaTeXStrings and Latexify hard dependencies, since they are only used by pgfplotsx backend;
• resolve methods ambiguities detected by Aqua;
• fix pie aspect_ratio bug (leading to a Gaston warning);
• syntax simplifications;
• cleanup dead code;
• improve coverage.

[BeastyBlacksmith]

• drop Contour, LatexStrings and Latexify hard dependencies, since they are only used by pgfplotsx backend;

What is the benefit of that? For one you loose the ability of specifying compat entries and its also a breaking change.

[t-bltg]

What is the benefit of that

Well, pgfplotsx is an optional backend, so should Contour and Latexify be optional dependencies for Plots. Maybe we should create a glue package for PGFPlotsX ?
LaTeXStrings is already a Latexify dependency, so it is a bit different, we can cheat by using Latexify.LaTeXStrings from within Plots.

Compatibility is still checked in here.

This ambiguity was spotted by Aqua tests as stale dependencies (since only triggered by @require).

[codecov]

Codecov Report

Attention: Patch coverage is 81.28655% with 32 lines in your changes missing coverage. Please review.

Project coverage is 82.22%. Comparing base (c5fa70c) to head (1b5e4e0).
Report is 425 commits behind head on master.

Files with missing lines	Patch %	Lines
src/recipes.jl	69.56%	7 Missing ⚠️
src/utils.jl	81.08%	7 Missing ⚠️
src/axes.jl	86.48%	5 Missing ⚠️
src/backends/hdf5.jl	42.85%	4 Missing ⚠️
src/backends/gaston.jl	83.33%	3 Missing ⚠️
RecipesBase/src/RecipesBase.jl	91.30%	2 Missing ⚠️
src/args.jl	80.00%	2 Missing ⚠️
src/backends.jl	84.61%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #4456      +/-   ##
==========================================
+ Coverage   80.83%   82.22%   +1.39%     
==========================================
  Files          40       40              
  Lines        8185     8077     -108     
==========================================
+ Hits         6616     6641      +25     
+ Misses       1569     1436     -133     

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[BeastyBlacksmith]

Well, pgfplotsx is an optional backend, so should Contour and Latexify be optional dependencies for Plots. Maybe we should create a glue package for PGFPlotsX ?

These are all packages where its not worth the hassle to put that much work into it over just shipping them. In principle I agree it would be nice to have a better mechanism for optional dependencies, especially because of compat. But that would need to land in Pkg first.

For reference:

julia> @time_imports using Contour
      4.6 ms  Contour
julia> @time_imports using Latexify
      0.6 ms  Requires
      0.9 ms  LaTeXStrings
     27.5 ms  MacroTools
      0.4 ms  Formatting
      4.6 ms  OrderedCollections
     32.9 ms  Latexify 41.86% compilation time (7% recompilation)

[t-bltg]

Thanks, I've removed the breaking PGFPlotsX changes, which should optionally be included in a future Plots 2.0.

[BeastyBlacksmith]

In principle I agree it would be nice to have a better mechanism for optional dependencies, especially because of compat. But that would need to land in Pkg first.

Relevant PR to track: JuliaLang/Pkg.jl#3216