Added concept of __make__.py module to segment package. MODEL.

Added three new segment commands:

    * make module - interpret (mmi)
    * make module - stub (mms)
    * make module - view (mmv)

Segment menu now looks like this:

    Red Example Score (2013) - segments - segment 01

        definition module - edit (e)
        definition module - edit at top (E)
        definition module - interpret (dmi)

        make module - interpret (mmi)
        make module - stub (mms)
        make module - view (mmv)

        pdf - version (pdfs)
        pdf - view (pdfv)

    >

MODEL: a new __make__ module is now used to produce segment output.pdf and
output.ly files. You can see this by listing the segment package:

    > ls

    __make__.py
    definition.py
    output.ly
    output.pdf

The __make__ module contains completely static contents:

    > mmv

    # -*- encoding: utf-8 -*-
    import os
    from abjad import *
    from definition import segment_maker

    lilypond_file = segment_maker()
    current_directory = os.path.dirname(__file__)
    ly_file_path = os.path.join(current_directory, 'output.ly')
    persist(lilypond_file).as_ly(ly_file_path)
    pdf_file_path = os.path.join(current_directory, 'output.pdf')
    persist(lilypond_file).as_pdf(pdf_file_path)

MODEL: the 'definition module - interpret (dmi) command is now deprecated.
This means that any __main__-executable logic at the foot of your segment
definition modules ...

    if __name__ == '__main__':
        lilypond_file = segment_maker()
        current_directory_path = os.path.dirname(__file__)
        ly_file_path = os.path.join(current_directory_path, 'output.ly')
        persist(lilypond_file).as_ly(ly_file_path)
        pdf_file_path = os.path.join(current_directory_path, 'output.pdf')
        persist(lilypond_file).as_pdf(pdf_file_path)

... should be removed.

Use (mmi) instead.