Overhaul attitude limits

[GHowardEng]

Don't depend on Accel vectors/angles to transition attitude between limits. E.g. roll change from 180 to negative 180 should be done post filtering and not dependent on z Accel magnitude.

[GHowardEng]

Still needs some work. Transitions between limits (eg roll from 0 to 180 when flipped) needs to be instantaneous (applied to final output). The 'filtered' trajectory causes issues with some other calculations.

[GHowardEng]

Suggestion - retain the conditioning of accelerometer angles (-180 to 180) and allow gyro estimate to propagate over the same range. Then set hard limit on final estimate that will switch sign of angle if abs > 180. This will allow smooth trajectories past 90 degrees but also have the instantaneous switching when passing the 180 degree limit