Use bash options to make scripts more robust

[chrisburr]

The bash lesson should recommend using some options at the top of scripts to make them easier to debug. My personal preference is to start scripts with

#!/bin/bash
set -euo pipefail
IFS=$'\n\t'

for the reasons listed here.

[alexpearce]

Agreed that these are useful. I often prefer to use the long-hand version for each flag, as it's a little more self-documenting: (and Googleable)

set -o errexit -o nounset -o pipefail

On the other hand, these lines are quite a lot like magic, especially the IFS line. Are we willing to explain what they do in the lessons?