need to quickly find out which packages a set of julia files are using. in my case, this was to create an environment after the fact... so I can ship it to people who have a clean install.
quick hack: grep through .jl files and find bits of text that start with "using"
not perfect, but got me 90% of the way there
grep "^\W*using" *.jl | cut -d: -f2 | sed s/using// | tr -d "[:blank:]" | sort | uniq