v0.3.0

Changed

• Switching between the wall and an enlarged camera no longer reconnects. The
  full-resolution feed starts the first time you enlarge that camera and then
  stays connected, so moving between the two views changes the picture at once.
• A camera sits at one connection while you watch the wall, and two after you
  have enlarged it once.
• Decoding uses one thread instead of one per core. Measured against the
  camera's own on-screen clock, that is 0.22s closer to live on a 1080p stream.
  The other low-latency flags were measured as well; they gave that back and
  are not used.

Fixed

• An enlarged camera whose full-resolution stream is refused, because the
  camera limits how many sessions it allows, now shows the low-resolution
  picture instead of an error.
• The wall keeps working on a camera that allows only one session.