listen for 'error' events from sclang and render them
feat(post-window): post notification when sclang dies
feat(repl): option to post to Growl/NotificationCenter on errors
style(post-window): display time of error
fix(repl): if sclang dies unexpectedly it would get stuck unable to simply recompile/relaunch

also only growl exit notification for unexpected deaths, not just when recompiling