viewer: add top margin to .chart-container (in case there's no reference check)

viewer: no need to compare to True, fixes two E712 warnings as well

viewer: hide dashed line in the chart if current check is not anywhere on it

viewer: skip failed checks in get_chart_data()

viewer: show tooltip for line chart

viewer: link to individual checks on the line chart

candolint: don't forget to check candolint.js too

viewer: use subqueries to get data on index page Before, there were bare columns in the aggregate query, their values were undefined (but it somehow worked), as SQLite docs say. Good news is that now this bigger query uses (project_id, ordinal) index and is really fast.

viewer: one more place needed an explicit order_by() call

viewer: the rest of the hover line bits for chart