Fast switch to another weather radar

[paulhoule]

BGM radar got shut down this week which caused an incredible flood of error messages from
my script.

I switched to TYX, which is OK, which required me to change a total of three files,
including the radar-config.yaml files and two HTML templates. It was also a
search-and-replace job where an instance of BGM could have been forgotten.

When we switch back to BGM, I want to make it single-step to select the weather radar.

Related to that is the possibility of having the system handle multiple radars at the
same time, the only real trouble there is how to lay them out in the web UI. Also
as a decision making tool, I only need one radar.