- change to boolean param

 - Ubuntu install NuttX toolchain, gazebo, and switch to python3
 - OSX switch to python3

This fixes the issue where the  DO_CHANGE_SPEED command was ignored and
the drone always travelled at the MPC_XY_CRUISE velocity.

It wasn't possible to fly faster than cruise speed even if planned
in the mission.

Limiting the planned cruise speed is necessary because
the smoothed trajectory mission plans to the _mc_cruise_speed and
if that's higher than the maximum it gets capped for safety by the
position controller and the result is a jerky flight.

simulator in hardware, new module added that allows to run a simulator in the hardware autopilot, for more documentation visit https://github.com/romain-chiap/PX4_SIH_QuadX

 - this extension adds support for Data Structure Description Language (DSDL)

* drivers, magnetometer: added ak09916 driver to support the mag driver emulated by the Here2 gps
* boards: set yaw 270 rotation for external ak09916 driver and only start it for the PH21
* drivers: only start ak09916 when icm20948 is not available on a ph21 setup

This should prevent future regressions when compiling with "Unix
Makefiles" or others instead of ninja as the generator behind cmake.

This fixes build races which happened if "Unix Makefiles" instead of
ninja-build was used as the cmake backend.

For any dependencies of commands on files we need to create a target.
Otherwise, if "Unix Makefiles" are used as the generator the commands
are run in parallel on the different files which often can lead to
races or redundancies in our build.

A nice write-up can be found here:
https://samthursfield.wordpress.com/2015/11/21/
cmake-dependencies-between-targets-and-files-and-custom-commands/#
custom-commands-and-parallel-make

   Addresses #11832 - configure the mixed use GPIO
   that can be the a BLue LED or a Heater as PUSH
   PULL on Cube as to not let the heater input float.

Add back pwm out sim module so HITL simulation works again.

    - ecl in PX4/Firmware (aed3d80d5982f37e8353d6d07e29c79a9260b086): https://github.com/PX4/ecl/commit/f95cd4b3584d029c35b288a39180ddf25b2dd004
    - ecl current upstream: https://github.com/PX4/ecl/commit/c4492b17c1d7bb9b74011efa9890452b091421e8
    - Changes: https://github.com/PX4/ecl/compare/f95cd4b3584d029c35b288a39180ddf25b2dd004...c4492b17c1d7bb9b74011efa9890452b091421e8

    c4492b1 2019-04-09 Martina - do not reset yaw if vehicle on ground
14227ea 2019-04-08 Julian Oes - CMakeLists.txt: fix cmake warning
f97f0b6 2019-03-30 Paul Riseborough - EKF: Remove unnecessary code
43b5e26 2019-03-02 Paul Riseborough - EKF: Fix bug causing continual yaw reset when EKF2_MAG_TYPE = 2

With 24 MHz accesses to the SD card were unreliable. And the chance of
failure recently got worse, so that logging became impossible.

 - needed for code coverage of python scripts

- platform is optional and matters for Visual Studio builds
- `ver` command shows the windows version
and was just my first CI test