octoprint: 1.2.9 -> 1.2.10

Note: the 1.2.9 GitHub tarball's sha256 has changed.

Changes:
- Fixed an issue introduced by the fix for 1196 that had the "Upload
  to SD" button stop working correctly.
- Fixed an issue causing an error on disconnect after or cancelling of
  an SD print, caused by the unsuccessful attempt to record print
  recovery data for the file on the printer's SD card.
- Only add bed temperature line to temperature management specific
  start gcode in CuraEngine invocation if a bed temperature is actually
  set in the slicing profile.
- If a communication timeout occurs during an active resend request,
  OctoPrint will now not send an M105 with an increased line number
  anymore but repeat the last resent command instead.
- Don't add an extra ok for M28 response.
- Add an extra ok for M29 response, but only if configured such in
  "Settings" > "Serial" > "Advanced options" > "Generate additional ok
  for M29"
- Trigger M20 only once after finishing uploading to SD
- Prevent M105 "cascade" due to communication timeouts
- Fixed wrong tracking of extruder heating up for M109 Tn commands in
  multi-extruder setups.
- Fixed start of SD file uploads not sending an M110.
- Fixed job data not being reset when disconnecting while printing.