Untracking a season clears `wanted` on every episode (§4.1) and leaves
the files where they were, so a season grabbed once and then untracked
rendered `0/0 eps` beside a column of green check glyphs. The same
counter could also read `10/1`, since the numerator was drawn from the
wanted set the denominator had already shrunk.
An episode now counts once it is wanted, on disk, or both, and the chip
is hidden rather than shown as `0/0` when a season or series accounts
for nothing. `Series.wanted_episodes` becomes `total_episodes`.
Miguel Palhas
dbce23f570