Sensor stream protocol

The hub program hardware/sensor_stream.py prints one line every 100 ms:

S,ms,heading,pitch,roll,yaw_rate,batt_mv,
  A_angle,A_speed,A_load, B_..., E_..., F_...,
  color,reflection,ambient,hue,sat,val

• 25 comma-separated fields. - means that device isn't plugged in.
• Heading: degrees, 0 at program start, clockwise positive (Pybricks). Pitch/roll: degrees. Yaw rate: deg/s.
• Motor angle: degrees, speed: deg/s, load: percent.
• Color: name (RED, WHITE, ... or NONE), reflection/ambient: 0-100, hue 0-359, sat/val 0-100.
• Any other line (normal print(), partial line) is ignored by work/pc/protocol.py.

Mission program lines (alliedwork.py)

These are printed by mission programs (not by sensor_stream.py), one per line:

Line	When	Example
T,<ms>,<x>,<y>,<heading>	every 200 ms while a command runs (TELEMETRY_MS)	T,4400,30.00,8.08,0.0
E,<ms>,<event>,<detail>	events: MISSION, RUN_START, RUN_END, STALLED, TIMEOUT, SQUARED, ERROR	E,4130,STALLED,drive
L,<ms>,<text>	log(text); the menu logs alliedwork <version> at start	L,22380,square done

work/pc/protocol.py currently parses only the S sensor lines; showing T/E/L live is on the roadmap.