Check For Minimum Version of Bash

[sshaw]

Hi, fun program, thanks! Just a suggestion to check for Bash 4.3 on startup:

[ ${BASH_VERSINFO[0]} -lt 4 -o ${BASH_VERSINFO[0]} -eq 4 -a ${BASH_VERSINFO[1]} -lt 3 ] && echo 'Bash >= 4.3 required' >&2 && exit 1