Removed example scores from main menu.

Example:

    Score manager - active scores

        1: Betörung (2012)
        2: Čáry (2006)
        3: Huitzil (2013)
        4: L'archipel du corps (2011)
        5: L'imaginare (2010)
        6: Lidércfény (2008)
        7: Mon seul désir (2009)
        8: Poème récursif (2005)
        9: Red Shift Hijinks (2005)
        10: Sekka (2007)
        11: Traiettorie inargentate (2013)

        scores - new (new)

    >

Use the new 'example scores - toggle (xst)' command to toggle example score
visibility.

Example:

    > xst

    Example scores visible.

    Press return to continue.

    Score manager - active scores

        1: Betörung (2012)
        2: Blue Example Score (2013)
        3: Čáry (2006)
        4: Green Example Score (2013)
        5: Huitzil (2013)
        6: L'archipel du corps (2011)
        7: L'imaginare (2010)
        8: Lidércfény (2008)
        9: Mon seul désir (2009)
        10: Poème récursif (2005)
        11: Red Example Score (2013)
        12: Red Shift Hijinks (2005)
        13: Sekka (2007)
        14: Traiettorie inargentate (2013)

        scores - new (new)

    >