PX4/Firmware — pull request #436 by DrTon (2013-09-30 21:08:55+00:00)
Title: position_estimator_inav fixes

- Fixed accelerometer bias estimation
- GPS validity conditions fixed
- Some debug code to catch NaN position bug on startup
- Some cosmetic fixes

Tested in flight, accelerometer bias estimation works nice, can be merged, but I want to catch the bug with NaN estimation first.