v1.5.0a23

• Receiver setup can now read and edit which NMEA sentences the u-blox
  transmits. The GPS card's "Receiver setup (u-blox)" section gained an NMEA
  sentences panel: Read current shows the chip's per-sentence output state
  (RMC/GGA/GLL/GSA/GSV/VTG, via UBX CFG-VALGET), toggles set them on/off on
  both UART and USB (optionally saved to flash), with RMC/GGA marked as what
  vanchor actually needs and a confirmation guard before turning RMC off (it
  carries the speed + course vanchor relies on). Fixes the "receiver only sends
  GGA/GLL" class of problem at the source instead of widening the parser.
  Bench-verified against a real M9N (VALGET read-back + GLL on/off round-trip).