human friendly pahr

[vidma]

@qqqlab I been confused to many times which direction is which so made this change from what I found in ahr.h
e.g.

pahr

roll:+27.7 (roll right) pitch:-4.3 (pitch down) yaw:+52.9 (yaw right)
roll:+8.1 (roll right)  pitch:-1.3 (pitch down) yaw:+50.0 (yaw right)
roll:-6.7 (roll left)   pitch:+0.9 (pitch up)   yaw:+48.5 (yaw right)
roll:-16.8 (roll left)  pitch:+2.5 (pitch up)   yaw:+47.2 (yaw right)

so it seems we're partially following this convention (except yaw direction is inverted)?

[qqqlab]

I like this, but I also like the less verbose "old" pahr...

Let's have both: rename the current pahr to pah (?) and add the new pahr. The docs refers to pahr, so new users get steered to the verbose version.

What do you think?

I've updated the AHRS documentation to explain the used local body frame (which is local NED).

[vidma]

@qqqlab updated