mulit_uavs

[robin-shaun]

Hello，我是肖昆，GAAS的老用户啦。这个是多机飞行的例程，有路径规划（给的是目标位置）和运动规划（给的是目标速度）两部分，展现的效果是四架飞机同时起飞，画四个同心圆。
由于当前的GAAS还不能发布目标速度，所以我把运动规划里我对px4_mavros_run.py做了较多的修改。

[ninawrong]

感谢 PR！我们尽快 code review 后提出反馈。

[Doodle1106]

I will give them a quick look and have a test on my setup, thanks for the PR.

[Doodle1106]

@robin-shaun I have tested your PR, and I will merge it at the moment, but can you later write a short description on how to use it? I didn't see the desired performance as you depicted before. The drones would take off simultaneusly but they were not flying along a circle.