v0.5.0

• The city is vector art now, drawn at the size it's shown: sharp at any zoom, and more detailed
  the closer you look (siding, shingles, window frames and sills, brick courses, wheels, grass,
  the crowd at the stadium). Zooming is smooth: scroll, pinch, or + and − ease in and out, and ⤢
  flies back to the whole city. Things move smoothly too, no longer on the pixel grid.
• 🎥 Follow (or C): the camera flies from one radio on the air to the next, following each
  while it talks, with a caption saying who it is; when it's quiet, it pulls back to where they've
  been. With Listen on, it follows the radios you're hearing.
• The city is drawn in chunks, in the background, the nearest first; the page draws as often as
  the screen does while the camera moves, and 30 times a second otherwise.