Streamlined SegmentPackageWrangler. INTERFACE.

There is now a clean parallelism between the material interface and the segment
interface.

MATERIALS:

    Red Example Score (2013) - materials - tempo inventory

        * 8=72
        * 8=108
        * 8=90
        * 8=135

       1: __init__.py
       2: __metadata__.py
       3: definition.py
       4: illustration.ly
       5: illustration.pdf
       6: output.py
       7: versions/

          definition.py - autoedit (da)
          definition.py - check (dc)
          definition.py - edit (de)
          definition.py - output (dp)

          illustration.ly - edit (ie)
          illustration.ly - interpret (ii)
          illustration.pdf - open (io)

          output.py - check (oc)
          output.py - edit (oe)
          output.py - illustrate (oi)

    >

SEGMENTS:

    Red Example Score (2013) - segments - A

       1: __init__.py
       2: __metadata__.py
       3: definition.py
       4: illustration.ly
       5: illustration.pdf
       6: versions/

          definition.py - edit (de)
          definition.py - illustrate (di)
          definition.py - stub (ds)

          illustration.ly - edit (ie)
          illustration.ly - interpret (ii)
          illustration.pdf - open (io)

    >