Draft: C++: Data Receiver for multiple endpoints

This is just some toying around with !321 (merged) and !178 (closed) to have a multi-endpoint receiver.

Works in a very basic level, but would need lots of work, among that:

• Handle exceptions thrown in pool receiver thread and pass to main satellite thread
• actually correlate actions somewhat with Satellite FSM states
• proper error handling
• rename stuff.

But the basic idea is for the user to simply implement their version of DataRecv::receive() and have fun with the data.