Merge pull request cyoung#657 from cyoung/ahrs_dev

Sync master with ahrs_dev (minor webui changes).

Merge pull request cyoung#641 from cyoung/ahrs_dev

AHRS for v1.4r1.

Ensure SensorQuaternion synced with IMUMapping.

Merge remote-tracking branch 'origin/master' into ahrs_dev

# Conflicts:
#	Makefile
#	main/equations.go
#	main/gen_gdl90.go

TEMPORARY: get latest 'goflying' packages in Makefile.

Ease up on the cpu.

Slip/skid indicates correctly in UDP; limit UI slip/skid to 10 deg max.

Remove auto-expand code. Increases microSD card failures.

web Makefile tried to copy nonexistent file.

IMU->ATT and BMP->ALT on UI indicators.