Connect to server - no timeout

[ZdenekM]

If the user enters a bad hostname/IP of the ARServer, there is "Connecting to server" displayed forever. There should be some (short) timeout and notification when an error occurs. Plus it would be good to use Trim() on the input - a user may accidentally enter e.g. space after the IP and then there is some unfriendly parsing error shown.

There should be also a timeout for connecting to the URDF storage (port 6780) and notification if an error happens.