v0.3.177-alpha

One important fix underneath, and a pass over the parts of the app you meet in
your first few minutes.

Fixed

• Your computer could throw away a piece of a model it had downloaded
  perfectly. Models are stored in pieces, and each piece has a fingerprint so
  a node can check it has not been damaged. The catch is that several versions
  of the same model exist — different people convert them, and the results are
  all valid but not identical, so their fingerprints differ. Another computer
  on the network could mention its version's fingerprint, your computer would
  take that as the answer, notice its own piece did not match, and delete a file
  that was never damaged. It then spent several minutes unable to use that model
  while it downloaded the piece again — and the piece that came back was
  identical, byte for byte, to the one it had just deleted. On the machine where
  this was found it was happening about once every nine hours, roughly half a
  gigabyte each time. A piece is now only deleted when it fails against a
  fingerprint taken from the model's original source, which is the only one that
  can actually settle the question. When there is no such fingerprint the file
  is kept and shared as before, and the disagreement is simply reported. If your
  node is on a small network and holds the only copy of something, this is the
  fix that stops it disappearing.
• A warning appeared at every startup saying network traffic could not be
  measured. It was not true. The counter genuinely has nothing to report for
  the first half-minute, because nothing has been sent yet, and the message
  confused that with the feature being broken. It now says nothing unless
  something is actually wrong.

Changed

• The row of icons along the top is now three places and a menu. There were
  seven small buttons up there whose only explanation was the label that appears
  if you hover, which does not exist on a touchscreen and is easy to miss
  anywhere else. Two of them did the same thing as Settings. Everything to do
  with running your node — its name, the stop button, connecting another
  machine, the automatic download status — now lives on the dashboard beside the
  thing it describes, and choosing your language or a light or dark theme lives
  in Settings, where people were already looking for it.
• The first screen no longer tells you to press a button that is not there.
  It suggested turning on private mode using a control in a bar above it. There
  is no such bar until a conversation has started, the button is called
  something else, and it only appears at all if your computer holds both ends of
  the model. It now describes what is actually in front of you.
• The coloured bar showing which parts of a model you have is explained.
  Every colour meant something and the only way to find out was to hover over
  it. There is now a key.
• Plainer wording in a few more places, and the setup guide no longer uses two
  different words for the same thing on adjacent lines.

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Full commit list: v0.3.176-alpha...v0.3.177-alpha