MockMapCanvas: Auto clean up after tests
Map#scrollZoom attribute

- makes it possible to disable scroll-to-zoom
  functionality (Google Maps and Leaflet only)
Animations: Refactor the way layers are removed to enforce the limit

- Thin layer times by time-interval instead of by index.
  For set of times with varying intervals (think past & future times),
  this provides a more evenly spaced animation, vs removing by index