Improved menu entry match logic.

This now works without surprise:

    Red Example Score (2013) - materials - magic numbers

        * 1
        * 3
        * 4
        * 7
        * 11
        * 18
        * 29
        * 47
        * 76
        * 123
        * 199
        * 322
        * 521
        * 843
        * 1364
        * 2207
        * 3571
        * 5778
        * 9349
        * 15127
        * 24476
        * 39603
        * 64079
        * 103682
        * 167761
        * 271443
        * 439204
        * 710647
        * 1149851
        * 1860498
        * 3010349
        * 4870847
        * 7881196

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

          __illustrate__.py - edit (le)
          __illustrate__.py - stub (ls)

          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)

          package - check (ck)
          package - version (vr)

    >

It was previously problematic to enter (1) or (3) because these numbers were
being interpeted as the numbers 1 and 3 in the material summary (1, 3, 4, 7,
...). The numbers (1) and (3) are now interpreted to mean assets #1
(__illustrate__.py) and #3 (__metadata__.py) and open accordingly.