New Default Small-C Categorical View

[alexsb]

Using colors for distinguishing categories in a single color comes with a host of problems. Hence, we should not do this by default. Instead, we should use the following visualization for categorical numbers with a small (<30) number of categories:

• Each category is represented by a "column". If an element is of that column, the cell is filled in with a lightish gray.
• The histogram bar in the header is aligned with the column.
• Hovering the bar in the histogram highlights all the elements of the category.
• The label uses a white stroke to make sure that the text is still readable even when it intersects with a filled in cell.

See also the Figma sketch for alternatives.