OpenTag Station v1.0.0-rc.20

Update a running station (keeps settings and calibration): in the station's web page open
Settings → Update and upload opentag-station-1.0.0-rc.20-application.bin from this release.

New station or recovery (erases settings and calibration): use the
USB installer, which installs this same build.

Spoolman 0.27 tag support

• Writing a tag now also links it to the spool in Spoolman's own tag list (Spoolman 0.27 or
  later). Moving a tag removes it from the previous spool first, and clearing a tag removes it.
  These steps are part of saving the link in Spoolman, so the existing retry and recovery
  prompts cover them.
• The station finds the spool through Spoolman's tag list first. A tag Spoolman links to a spool
  is recognised even if it holds no OpenPrintTag data, for example a blank tag you linked in
  Spoolman yourself: Home shows its spool, and Weigh and Assign work.
• Tag IDs are matched in both byte orders, because some phones report them reversed.
• On Spoolman 0.27 or later the two extra fields are optional. When they exist the station still
  fills them; when they don't, it uses Spoolman's tag list only and no longer warns about them.
• Each tag placed on the station is reported to Spoolman, so a Spoolman page paired with the
  station (Spoolman: Settings > Tag Scanning) jumps to its spool.
• A tag that Spoolman links to a filament, or to two spools, is refused before anything is written.

Fixes

• Saving weights works with every Spoolman 0.26 and 0.27 release, not only 0.26.1.
• After start-up or a Spoolman outage the station learns Spoolman's version again right away.
  Before, weight saving could stay off for up to five minutes.
• A tag at the edge of the reader's range no longer flickers: one missed check is tolerated, and
  a read that fails part-way is retried after half a second instead of showing an error and
  waiting five seconds.