Subsystem_info status flags & checks: Switch back to uORB for inter-process communication, handle GPS checks completely inside ekf2, add distance_sensor checks

Subsystem_info status flags & checks : Initial commit, updating the health flags in a centralized way mostly in commander and the votedSensorsUpdate function.

to disable automatic evaluation of /dev/ttyS* expression in cygwin.
On linux verbatim seems to be default anyways. At least it doesn't get
evaluated on linux.

fw_att_control: Fix bug that caused the rudder to stutter when FW_RLL_TO_YAW_FF>0 and aileron input was supplied

    - sitl_gazebo in PX4/Firmware (bbc104ad): https://github.com/PX4/sitl_gazebo/commit/371e7c36c34d7dd45da5602a14a6ee01e9fe74db
    - sitl_gazebo current upstream: https://github.com/PX4/sitl_gazebo/commit/e8b3624b9dad63a492ae58c1ce8661488128966b
    - Changes: https://github.com/PX4/sitl_gazebo/compare/371e7c36c34d7dd45da5602a14a6ee01e9fe74db...e8b3624b9dad63a492ae58c1ce8661488128966b

    e8b3624 2018-06-04 Elia Tarasov - tune gimbal pid gains
54c256d 2018-06-05 Poutshi - Update README.md (#211)
1992b0d 2018-06-05 TSC21 - CMakeLists: fix targe msg links
10b0597 2018-06-01 TSC21 - validade_sdf: fix typo
8fee88e 2018-06-01 TSC21 - travis_ci: add catkin build
de983cc 2018-05-31 TSC21 - generate separate protobuff libs for each msg category
6cb9360 2018-05-31 TSC21 - restructure proto msg API (rename, organize list)
5a250a2 2018-05-31 TSC21 - proto msgs: use PascalCase convention
ea6e2da 2018-05-31 TSC21 - remove the rotors_ prefix from plugin names
7989043 2018-05-31 TSC21 - allow building with the most recent C++ compiler available on the host
b819817 2018-05-31 TSC21 - package.xml: update and reorganize package list
a20bf63 2018-05-31 TSC21 - CMakeLists: reorganize build target and dependecies list
ae7df80 2018-05-31 TSC21 - CMakeLists: remove exception for ROS when building gazebo_geotagged_images_plugin (no longer applicable)
0a4e27b 2018-05-31 TSC21 - CMakeLists: fix typo on building gazebo_motor_failure_plugin
27f977b 2018-05-31 TSC21 - gazebo_mavlink_interface: add support for Gazebo 9 for model_param func
eded9b2 2018-05-31 Elia Tarasov - set default pid gains as constants
29b5424 2018-05-31 Elia Tarasov - add default pid control gains to sdf xml
4caf496 2018-05-30 Elia Tarasov - move pid control gains to sdf xml

fix rgbled On and Powersave value in read mode.
In read mode, the ENABLE and SHDN is in bit 4 and bit5, so we may need a 4bit left shift to get a correct value.

Fixes the following corner case:
mpu9250 start -R
This would return a valid result (myoptind < argc), but myoptind pointed
to a NULL argument (and thus mpu9250 would crash).
With this patch, px4_getopt will return '?', indicating a parser error.

Update year to 2018