Handle cue point from OCS.

[zls29]

:book: Summary

OCS currently returns a cue when firing start messages. Previously gcs did nothing with this, and just played upon receiving the first start. To support starting from an arbitrary breakpoint, a check for cue number has been added.

:mag: Details

Needs testing.

:heavy_check_mark: Testing

• [ ] Simulate
  • [ ] All drones
  • [ ] Only 1 nonzero drone
• [ ] Real Life
  • [ ] All drones
  • [ ] Only 1 nonzero drone

:heavy_check_mark: Verification

• [ ] Checked for memory leaks