TODO

 / Make locations/zooms/iterations linkable, like with previous version
    / Maybe a leaflet Handler for hashchange events?
    / Make it read the hash on page load
    / Fix bug where it (sometimes? After reloading the page?) redraws
      unnecessarily after panning)
    / Use actual complex coords in URL
 / Prune pending jobs if they're out of bounds of the view (perhaps in
   getNextJob)
    / Wow, I just can't figure this out. I've tried bounds checking the tiles,
      but the wrong ones get pruned, either way I try to clear the jobs!
      Something stupid is happening, clearly...
      / Right, it seems to be that tiles are getting an inverted
        y (latitude/imaginary) coordinates... But that doesn't explain why
        *some* tiles were getting culled and others weren't?
 / Add some optimizations (see wikipedia page)
    / Cardioid/bulb-checking
    - periodicity checking
 - Fix rendering with a non-default tileSize
    - A tileSize of 128 is probably optimal for performance and initial scale,
      but then scale shouldn't depend on tileSize. MandelbrotLayer/Renderer
      need to account for tileSize (or somehow be independent of it).