Add grbl status icons to mainwindow

- added icon showing spindle state
- added coolant icon
- added tool number and feed rate icons
- refactored the incorrect measurement parser
- cosmetic formatting fixes
- manual commands should not have \n appended at
  origin - they get added later anyway and it stops
  the code matching strings it should recognize as
  commands we know about
Fix some movement-detected logic

At each stage of the sequence it was overwriting the status from the
previous steps.