Provide `--package` option for drush features-list (fl)

Forgive me if this is a duplicate. I searched for this issue and didn't see anything.

More and more modules are providing example features bundled with them. This is AWESOME, don't get me wrong. But this results in a ton of disabled features that appear with the features-list command. This makes it harder to see when some of my custom features are disabled.

Seems like a good solution would be a --package="My features package name" option that only lists those features.

Also, should package name show up as a column? Might make it kinda cramped, I don't know.