Feature Request: Add methods for returning higher-level orientation structs

[quietlychris]

I realize that this library is likely intended for lower-level use, but I was wondering if it might be of interest to make some level of preliminary sensor fusion across the onboard sensors used for attitude available directly. The examples have some methods like Navigator::read_all() return SensorData containing several first-party AxisData structs. For some other IMU/AHRS-related crates, those sensors instead return something like a mint::Quaternion or EulerAngles, which are generally more useful for the implementation of autopilots or other autonomy-related code. I know I'd be interested in being able to access something similar using the Navigator's hardware!

[quietlychris]

Since SensorData provides the 3D AxisData, it might be feasible to use the ahrs crate, which takes a set of nalgebra Vector3 structs as input from the gyroscope, accelerometer, and magetometer for an AHRS system via the Madgwick algorithm to create a nalgebra::Quaternion as an output. (I haven't tested this on hardware yet, this is just background at the moment).

However, since the RPi boards aren't hard real-time boards, the lack of a current API for ergonomically managing the jitter per this issue might require some testing as well. It would probably make the most sense to have this gated behind a feature flag if it were to be implemented on the navigator-rs crate directly. It might make more sense to just leave this up to users to implement that conversion directly on their application instead, although I think that having basically a "reference implementation" for sensor fusion available directly could also be nice.