* ekf2: Add FirstOrderLpf and InnovationLpf classes for innovation lowpass filtering
* ekf2: use InnovLpf filter class in preflight checks
* ekf2: move selection of yaw test limit for pre-flight check in function
* ekf2: Move pre-flight checks into separate function
* ekf2: use static constexpr insetead of inline for sq (square) function
* ekf2: Split pre-flight checks in separate functions
Also use the same check for all the innovations:
innov_lpf < test and innov < 2xtest
* ekf2: Add optical flow pre-flight check
* ekf2: Combine FirstOrderLpf and InnovationLpf in single class
* ekf2: check vel_pos_innov when ev_pos is active as well
* ekf2: transform InnovationLpf into a header only library and pass the
spike limit during the update call to avoid storing it here
* ekf2: Static and const cleanup
- set spike_lim constants as static constexpr, set innovation
- set checker helper functions as static
- rename the mix of heading and yaw as heading to avoid confusion
* ekf2: use ternary operator in selectHeadingTestLimit instead of if-else
* ekf2: store intermediate redults in const bool flags. Those will be used for logging
* ekf2: set variable const whenever possible
* ekf2: create PreFlightChecker class that handle all the innovation
pre-flight checks.
Add simple unit testing
Use bitmask instead of general flag to have more granularity
* PreFlightChecker: use setter for the innovations to check instead of sending booleans in the update function
This makes it more scalable as more checks will be added
* ekf: Use booleans instead of bitmask for ekf preflt checks
Rename "down" to "vert"