Fix Broken Ctrl-C

Ctrl-C handling seem broken:

• Threads that were spawned before setting the ctrl-c handler seem to stop directly when ctrl-c is hit. This can be see in current releases, as all execution forwarding stops. It can also be seen in older release, where hitting ctrl-c breaks the ssh transport and generates -43 errors.
• Scheduler command receives the SIGINT, while it should not.
• Finally, we want to be able to modify the ctrl-c behavior as the program changes. Indeed, at first, no allocation is made, reason why we shouldn't try to cancel it.