Made long assets lists bicolumnar.

Example:

    Score Manager - materials

       1: example articulation handler (Abjad)                22: fused yellow time signatures (Gebiete)
       2: example dynamic handler (Abjad)                     23: pitch classes (Gebiete)
       3: example notes (Abjad)                               24: split cobalt time signatures (Gebiete)
       4: example numbers (Abjad)                             25: split yellow time signatures (Gebiete)
       5: example pitch range inventory (Abjad)               26: tempo inventory (Gebiete)
       6: example sargasso measures (Abjad)                   27: time signature pairs (Gebiete)
       7: example markup inventory (Abjad) (AE)               28: tratti del arco (Gebiete)
       8: baca numbers (Bača)                                 29: yellow divisions (Gebiete)
       9: test rhythm marker (Bača) (AE)                      30: aggregates (Las manos mágicas)
      10: aggregates (Betörung)                               31: black pcs (Las manos mágicas)
      11: indigo pitch classes (Betörung)                     32: turquoise pcs (Las manos mágicas)
      12: range inventory (Betörung)                          33: magic numbers (Red Example Score)
      13: reiterated forte (Betörung)                         34: time signatures (Red Example Score)
      14: speckled rhythm maker (Betörung)                    35: instrumentation (Red Example Score) (AE)
      15: tempo inventory (Betörung)                          36: pitch range inventory (Red Example Score) (AE)
      16: time signature pairs (Betörung)                     37: tempo inventory (Red Example Score) (AE)
      17: violet pitch classes (Betörung)                     38: pitch classes (Traiettorie inargentate)
      18: cobalt divisions (Gebiete)                          39: tempo inventory (Traiettorie inargentate)
      19: end incised double valued note maker (Gebiete)      40: tuplet cell treatments (Traiettorie inargentate)
      20: end incised note maker (Gebiete)                    41: white flautando spanner (Traiettorie inargentate)
      21: fused cobalt time signatures (Gebiete)

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

    >