Confusing vertical velocity reporting

[dustin]

I originally reported this in TauLabs/TauLabs#2026 where I took off and immediately had a negative climb rate although the altimeter seemed to be tracking fine.

http://gfycat.com/GlassImpartialHydra

A more recent clip shows that it at least seems to be lagging behind.

http://gfycat.com/WelcomeWeakBlacklab

[mlyle]

@dustin -- can you try setting AttitudeSettings.VertPositionTau from 2.0 to 0.9? That's a reduction of 2.2x; it'll make the vertical position filter listen much more to the baro and much less to the Z accelerometer and past trend.

I'm curious if this A) looks significantly better on the OSD, and B) if altitude hold flies all right / better after this.

[mlyle]

Idea: don't pass DC on accelerometer on cfvert.