Allow to stack cases in multiples mode

[boogheta]

• [ ] add interface checkbox in cases title when in multiples
• [ ] handle proper fields:

  all tested = {
  tested negative
  + confirmed = {
    recovered
  + sick = {
       confined
     + hospitalized
     + intensive_care
  }
  + deceased
  }
  }

  adjust cases legend?

• [ ] use different level strokes to display contours