FeatureRequest: Replay-bot does not need to send data when no fgcom client is connected

[hbeni]

Currently the replay bot just sends data and leaves it to the server to sort that out.

• However, we might pause actual sending data when no valid fgcom-mumble clients are connected, which will save some bandwith.

• Also it might be desirable to just send when potential clients are in range, based on rough frequency range (uhf/vhf/hf).

This should of course be optional and controllable by appropriate switches.

[hbeni]

I really dislike the idea to duplicate the radio models in lua space.
Maybe there is an option to reuse the c++ models (can lua use c libs? Or maybe a custom binary like the test tool that the bot can optionally query?)

edit: looks like it can:

• https://www.lua.org/pil/26.2.html
• and os.execute
• or if supported http://www.lua.org/manual/5.1/manual.html#pdf-io.popen