v0.2.1

• Vehicles move smoothly along the roads: each step is the 2-across, 1-down of isometric pixel art,
  where before x and y rounded on frames of their own and sprites jiggled. They round corners
  instead of hopping from one lane to the other.
• Fixed: a radio's name bubble floated over the empty space beyond the map while its vehicle was
  out there, out of sight.