This makes sure that poll() never returns immediately.
accel & mag are only updated to keep the code in sync.

Should some of these be of interest to someone, we should create a profile.

Copy/paste logic in rc.interface to group MIXER and MIXER_AUX logic, alphabetize hardware list in rc.interface, alphabetize set/unset lists in rcS, and add -p argument to pwm failsafe calls per issue #9775.

Group instances of UAVCAN logic into a single block and copy/paste/regroup OUTPUT_MODE logic to form on block of code handling OUTPUT_MODE.

   FMUv5 has singlewire support

   This is a stubbed out version that will rely on the hardware
   manifest moving forward.

    - sitl_gazebo in PX4/Firmware (a08fc0c3ff3cfb4bba57035c98b0a7398b0c2a19): https://github.com/PX4/sitl_gazebo/commit/ac54b8fdddd9b21dbe6d59deaf46494864858bc9
    - sitl_gazebo current upstream: https://github.com/PX4/sitl_gazebo/commit/c1ca87e37b831cd4b64ac642957e701875738909
    - Changes: https://github.com/PX4/sitl_gazebo/compare/ac54b8fdddd9b21dbe6d59deaf46494864858bc9...c1ca87e37b831cd4b64ac642957e701875738909

    c1ca87e 2018-07-16 Elia Tarasov - add support for gazebo version greater or equal 9
eb4494d 2018-07-16 Elia Tarasov - load rotation signs from sdf model file
c00b9ee 2018-07-16 Elia Tarasov - add default constants for rotation signs
36360c5 2018-07-16 Elia Tarasov - add rotation signs to class variables

    - jMAVSim in PX4/Firmware (e2eb8404): https://github.com/PX4/jMAVSim/commit/e0e8b6ca473a6eecc3ee2984ea414e321f6808c6
    - jMAVSim current upstream: https://github.com/PX4/jMAVSim/commit/136e92eb8a0131b63c165d5f32dd74c3a2b28993
    - Changes: https://github.com/PX4/jMAVSim/compare/e0e8b6ca473a6eecc3ee2984ea414e321f6808c6...136e92eb8a0131b63c165d5f32dd74c3a2b28993

    136e92e 2018-07-16 Hamish Willee - Merge pull request #77 from PX4/readme-update-for-blender
78b653e 2018-07-10 alessandro - typo fix
9734edf 2018-06-20 alessandro - Addressing review comments from #77
a197e76 2018-06-19 Alessandro Simovic - readme: added instructions for Blender