controller. The yaw acceptance is defined by the mission item. If the pos
control sets it to NAN, then the yaw at a waypoint is ignored.

 - add to AddressSanitizer and UndefinedBehaviorSanitizer to CMAKE_BUILD_TYPE options
 - handle environment variable helpers outside of CMake
 - add -O1 optimization
 - cleanup whitespace

 - relative to the PX4 source directory root

- nuttx in PX4/Firmware (f3cbd3c744e9224bd55597fbfae23c56ce296544): https://github.com/PX4-NuttX/nuttx/commit/98a89513060c42215e9cd14f52a7fd7dcc08dacc
    - nuttx current upstream: https://github.com/PX4-NuttX/nuttx/commit/e31e94f5bd3cf68b9ed0f010724ac9122730dd21
    - Changes: https://github.com/PX4-NuttX/nuttx/compare/98a89513060c42215e9cd14f52a7fd7dcc08dacc...e31e94f5bd3cf68b9ed0f010724ac9122730dd21

    e31e94f 2018-09-21 David Sidrane - [REJECTED] kinetis:usbdev use CONFIG_KINETIS_USBOTG_PRIO at default

To reduce flash usage, until we can disable the FW & VTOL modules.

Modify 500001_axialracing_ax10 to utilize rc.ugv_defaults to allow deprecating rc.axialracing_ax10_apps and rc.axialracing_ax10_defaults and update CMakeLists.txt.

with:
- shutdown command support in SITL
- pyyaml included for RTPS message generation

Signed-off-by: Roman <bapstroman@gmail.com>