Tracking issue: Categorical data in Grapher

[sophiamersmann]

Supersedes #1264

Opportunities

• Use ordinal data to sort map legends and scatter plot legends
  • Issue: Support custom ordering in scatterplot legend #1690
  • Related: Admin: Add support for manually ordering legend items in maps #2710
• Use type information to choose better colour palettes (e.g. for ordinal variables)
• Data table: treat columns with categorical data differently than numerical columns
  • ✨ (data-table) hide change columns for non-numerical data #3094
  • Data table: Wide columns make it difficult to read the table #3044
• Improve map sparklines for string data, see Map sparklines should become levels for categorical variables #1323
• Visualising categorical data over time Chart views for categorical indicators #4178
• Design: not enough space in legend to explain categorical variables #1325
• ... probably more (please feel free to add to this list)

Background

Once #3362 and #3375 land, the following data types will be known to Grapher:

• Numeric
• Integer
• String
• Ordinal (subclass of String)
• NumberOrString (essentially a mixed type)