Improved remove package user experience.

Remove unnecessary blank lines.

OLD:

    Blue Example Score (2013) - materials

       1: flamingo

          materials - copy (cp)
          materials - new (new)
          materials - remove (rm)
          materials - rename (ren)

    > rm

    Enter material packages(s) to remove> 1

    Will remove /Users/trevorbaca/Documents/abjad/scoremanager/scores/blue_example_score/materials/flamingo

    Type 'remove' to proceed> remove

NEW:

    Blue Example Score (2013) - materials

       1: flamingo

          materials - copy (cp)
          materials - new (new)
          materials - remove (rm)
          materials - rename (ren)

    > rm

    Enter material packages(s) to remove> 1
    Will remove /Users/trevorbaca/Documents/abjad/scoremanager/scores/blue_example_score/materials/flamingo
    Type 'remove' to proceed> remove

The grouping better bundles related commands in the exchange.