[FIX] Color widget failed after removing Variable.make

[janezd]

Issue

After removing Variable.make, OWColor fails when loading settings because it tries to set Variable.name when loading settings.

The widget was misbehaving badly. set_data constructed the output table(!) and modified its attributes (not only colors but also names!). This most probably also broke Domain's dictionary _indices.

Description of changes

Fixing this required reimplementing the way in which the widget stores the data. Instead of storing variables, it stores the data (names, colors) and constructs variables before sending output.

#3822 could have also been the result of the questionable behaviour of the widget and may be fixed with this PR.

Includes

• Code changes
• Tests
• Documentation

[codecov]

Codecov Report

Merging #4041 into master will increase coverage by 0.07%.
The diff coverage is 96.64%.

@@            Coverage Diff             @@
##           master    #4041      +/-   ##
==========================================
+ Coverage   85.47%   85.55%   +0.07%     
==========================================
  Files         385      385              
  Lines       69107    69059      -48     
==========================================
+ Hits        59068    59080      +12     
+ Misses      10039     9979      -60

[markotoplak]

@janezd: you intentionally deleted ordered_values, right?

[janezd]

@janezd: you intentionally deleted ordered_values, right?

Yes. We haven't use them, as far as I know and check.