Ctrl-C in pulp repl can cause exit #342

To reproduce, type pulp repl and then hit Ctrl-C a few times, or hold it down if that doesn't work.

Result:

$ pulp repl
PSCi, version 0.11.7
Type :? for help

import Prelude
> 
> 
purs: Interrupt

Migrated from purescript/purescript#3269

I am pretty sure this is to do with how node handles subprocesses. I think it might be worth investigating how we might be able to get pulp repl to work without having it run as a subprocess of a Node process (ideally in a way which works on Windows too).