Fix for issue #27: add explicit socket close on ABORT

Adds a condition handler that traps ABORT signals and allows `ros_relay` and `ros_state` to properly shutdown and close any open sockets. This solves the issue where sockets on the controller remain in WAITING or OPEN state, confusing the ROS client programs (no data coming in, but still connected, while server programs have already been terminated).

Could potentially create conflicts with old versions of `ros_relay` and `ros_state` as I had to introduce a new variable (`shutdwn_req_`).

Tested on simulated and real R-30iA, HandlingTool V7.70

I assume the condition handlers are limited (i.e. a certain number are allowed).  Are we reserving one for ROS-Industrial?  Could this conflict with other kl programs?  Should we take the first or is it better to reserve the last condition handler?