Add span elements to hold the text of selected filter options
Update width of select filter on reset

The width shall be adjusted to the width of the default option text.
Copy the category name of selected option to a separate span
Display total, unpadded, as short text in select lists

The selected category name is now displayed in a separate span,
out of the list.
Bug fix: reset selection in total contributions filter

The default item has value "1", not "" in total contributions
filter. Note that for the same reason, the code in
getTotalAuthorsInCategory() will read the total number
of authors from the categories data rather than using the
short cut for the total contributions filter. This is
not a problem, however, since the default item is
present in the set of categories for total contributions,
which is not the case for other filters.
Return an empty string for an option without text in getOptionText()
Do not expand selected options in other lists after a selection

I updated the code to take into account whether the option is
currently selected and whether it is currently displaying its
short text or its long text.
Add CSS classes to filter lists and associated span for selected text
Add the same CSS class to hidden select for text width measurement
Style filters as exponents, with a Swiss design inspiration
Move selected / total authors from main area to menu
Change font weigth from Bold to Light
Reduce line height from 1.4 to 1.2
Move visualization/data selector back to the main area
Generalize the styles to all lists

I have also added a span to display the value selected
in the grouping selection. The behavior to update this
selected value shall be added next.