Added home breadcrumb.

Home screen now looks something like this:

    Abjad IDE - home

        example scores:
           1: blue example score
           2: etude example score
           3: red example score
        example stylesheets:
           4: clean-letter-14
           5: clean-letter-16
           6: rhythm-letter-16
           7: time-signature-context
        library: makers:
           8: zagged pitch class maker
        library: materials:
           9: baca numbers
          10: talea rhythm maker
          11: zagged pitch classes
        library: stylesheets:
          12: baca-letter-14
        scores:
          13: aracilik
          14: archipel
          15: betoerung
          16: cary
          17: chrysanthemums
          18: desir
          19: imaginaire
          20: krummzeit
          21: lidercfeny
          22: mannigfaltigkeiten
          23: manos
          24: recursif
          25: red shift
          26: sekka
          27: tack
          28: territoires
          29: traiettorie
          30: zeit

    >