Filter packages list of irrelevant sub-directories
Filter packages list of irrelevant sub-directories

I'm sure the package's API has a documented way of filtering the package
list, but fuck it, `loadFromCore()` is faster and doesn't require poking
through crappily-documented, moribund codebases.

Hopefully won't be using Atom for too much longer, anyway.

Alhadis/Atom-PhoenixTheme