Port expander driver first hacky version
position_estimator_inav: remove acceleration from state and INAV_W_XXX_ACC parameters, more NaN checks
Merge pull request #1009 from PX4/inav_fix

position_estimator_inav: stability fix
Merge branch 'master' of github.com:PX4/Firmware into pca8574
PCA8574 driver: Cleanup, ready for final testing and production
Enable the driver as default for boards having it
PCA cleanup: Full interfaces ready for AP use
Merge pull request #1024 from PX4/pca8574

PCA port expander