Updated tox.ini to properly clean out pycs.
Added scoretools.DrumNoteHead. NOTE.

NOTE. You can now create "drum" notes for use in a DrumStaff context.

The LilyPondParser will attempt to parse valid drum pitches ('snare', 'tamb',
'bd' etc) into DrumNoteHeads. Additionally, Chord and Note now accept
DrumNoteHead instances in place of NoteHeads.

To create drum music, use the following recipe:

    drums = Container('hihat4 hh bassdrum bd')
    drum_mode = indicatortools.LilyPondCommand(
        'drummode',
        format_slot='before',
        )
    attach(drum_mode, drums)
    drum_staff = Staff(
        music=[drums],
        context_name='DrumStaff',
        )

The results in a properly constructed piece of drum music:

    >>> f(drum_staff)
    \new DrumStaff {
            \drummode
            {
                    hihat4
                    hihat4
                    bassdrum4
                    bassdrum4
            }
    }