tools: add buttonc: send key events from stdin
pointerc: support button events
pointerd: support button events
pointerd: exit cleanly on SIGINT
motion-control: signal: set SA_RESTART
gy-801-dump: signal: set SA_RESTART
motion-control: reduce yaw downscale
this make movements (subjectively?) more friendly in general case
sensors::L3G4200D: enable high-pass filter @0.05hz
this helps with fighting nearly-constant drift
ahrs: complementary: ignore yaw from tilt
math::quaternion: add from_euler
add controlling client for gy-801
add pointer controlling over udp
math::quaternion: remove early test leftovers
ahrs: tilt: guard against acos(>1), acos(<-1)
ahrs: implement complementary filter
ahrs: tilt: fix direction
gy-801-dump: bump gyro read rate
gy-801-dump: perform quaternion forward integration