Fix issue #111, Ctrl-c at post init action queue quits terminal

We no longer trap the interrupt. We don't need to. The queue will be executed eventually, even if they ctrl-c it.
The user doesn't have a choice, by contract we state that anything in the mbs-do queues will be executed post load.
Even if the user interrupts, they will run eventually.

modified:   ext/mbs-do.sh