Other unrelated changes are: a) fixed typo in 'esitmate_velocity' to 'estimate_velocity'. b) moved init_compass from system.pde to sensors.pde which seemed consistent with other sensors.
git-svn-id: https://arducopter.googlecode.com/svn/trunk@1933 f9c3cf11-9bcb-44bc-f272-b75c42450872