camera trigger and camera capture publish on two different topics and camera feedback module uses CAM_CAP_FBACK param to choose between the two.

camera_trigger.msg: add feedback field to understand if message camera from trigger or capture driver

    - gencpp in PX4/Firmware (ed8517a7d97f15cdf556cdc64496cc72bebb99ab): https://github.com/ros/gencpp/commit/b41ee3060badd660662e21cd9d4f81971c87a420
    - gencpp current upstream: https://github.com/ros/gencpp/commit/7e446a9976916a7b6fc7266098c67fc6f73a76e0
    - Changes: https://github.com/ros/gencpp/compare/b41ee3060badd660662e21cd9d4f81971c87a420...7e446a9976916a7b6fc7266098c67fc6f73a76e0

    7e446a9 2019-01-25 James Xu - enable Windows build (#38)

    - genmsg in PX4/Firmware (d4338773aa0139295caff03dc8275b44b88ccd04): https://github.com/ros/genmsg/commit/42e364661025b8f3d51486dc513d9e29cbd308da
    - genmsg current upstream: https://github.com/ros/genmsg/commit/5736b1f7ad037fb5811a3100ba9da2db0ec1f20a
    - Changes: https://github.com/ros/genmsg/compare/42e364661025b8f3d51486dc513d9e29cbd308da...5736b1f7ad037fb5811a3100ba9da2db0ec1f20a

    5736b1f 2019-01-28 Dirk Thomas - add missing run_depend on empy (#81)

Signed-off-by: CarlOlsson <carlolsson.co@gmail.com>

uorb_to_ros_msgs: delete all messages on the out dir first, so it can also consider message deletions on the input dir

 - <cinttypes> isn't available in the NuttX c++ library

- Use the values from landing_gear.msg

- landing_gear: refactor state name
- Add the keep state to the landing gear message
- Adapt FlightTaskManual, FlightTaskAutoMapper, mc_pos_control,
to review message definition

- An new message is created just for the landing gear
- The old logic is repalaced by publishing this new topic

* attitude and rate setpoint message: use 3D array for thrust demand
* FixedWingAttitudeControl: rework airspeed scaling
  * move airspeed and scaling calculation into separate method
  * if vtol in hover and airspeed disabled use minimum airspeed instead of trim airspeed

- move the update after the integration: a new computed jerk has an impact at the next epoch only
- add jerk reduction in case of too large integration time: when a jerk of "min_jerk" during dt is too much
- add jerk reduction if the integration time is larger than the predicted one and that integrating that jerk would lead to an acceleration overshoot
- rename some variables

obstacle_distance: update distances description according to latest obstacle_distance mavlink message