PolyScope hangs when connecting to a port that doesn't have a script sender running

[urfeex]

When the remote (as configured by IP and port in the URCap's settings) does have something else running on that port, this URCap will try to fetch the script code nevertheless and expect a valid answer. If no answer is received, however, the program will hang until the remote port is closed.

I would suggest adding a timeout for receiving an answer. Note: This is only relevant if there is something running on the configured port and that accepts the remote connection, but never answers the "request_program" request.

This came up in UniversalRobots/Universal_Robots_ROS_Driver#757 but is also relevant for PolyScope 5 and ROS 2.