Cleaned up segment management menu.

Now looks like this:

    Red Example Score (2013) - segments - segment 01

        __init__.py - open (ipyo)                          system - LilyPond log (ll)
        __init__.py - write stub (ipyws)                   system - Python (pyi)
                                                           system - commands (?)
        __make__.py - interpret (mpyi)                     system - doctest (pyd)
        __make__.py - open (mpyo)                          system - pytest (pyt)
        __make__.py - write stub (mpyws)                   system - quit (q)
                                                           system - session variables (sv)
        __metadata__.py - open (mdpyo)                     system - shell (!)
        __metadata__.py - rewrite (mdpyrw)
                                                           versions - definition.py - open (vdpyo)
        definition.py - edit (dpye)                        versions - output.ly - open (volyo)
        definition.py - write stub (dpyws)                 versions - output.pdf - open (vopdfo)

        edit - score stylesheet (ess)

        go - back (b)
        go - home (h)
        go - score (s)

        go - next score (>>)
        go - next asset (>)
        go - previous score (<<)
        go - previous asset (<)

        go - build (u)
        go - distribution (d)
        go - makers (k)
        go - materials (m)
        go - segments (g)
        go - stylesheets (y)

        metadata - add (mda)
        metadata - get (mdg)
        metadata - remove (mdrm)

        output.ly - interpret (olyi)
        output.ly - open (olyo)

        output.pdf - open (opdfo)

        package - version (ver)
        package - versions list (verls)

        repository - add (rad)
        repository - clean (rcn)
        repository - commit (rci)
        repository - revert (rrv)
        repository - status (rst)
        repository - update (rup)

    >
Removed extra intercolumnar whitespace.

Example:

    Red Example Score (2013) - segments - segment 01

        __init__.py - open (ipyo)             system - LilyPond log (ll)
        __init__.py - write stub (ipyws)      system - Python (pyi)
                                              system - commands (?)
        __make__.py - interpret (mpyi)        system - doctest (pyd)
        __make__.py - open (mpyo)             system - pytest (pyt)
        __make__.py - write stub (mpyws)      system - quit (q)
                                              system - session variables (sv)
        __metadata__.py - open (mdpyo)        system - shell (!)
        __metadata__.py - rewrite (mdpyrw)
                                              versions - definition.py - open (vdpyo)
        definition.py - edit (dpye)           versions - output.ly - open (volyo)
        definition.py - write stub (dpyws)    versions - output.pdf - open (vopdfo)

        edit - score stylesheet (ess)

        go - back (b)
        go - home (h)
        go - score (s)

        go - next score (>>)
        go - next asset (>)
        go - previous score (<<)
        go - previous asset (<)

        go - build (u)
        go - distribution (d)
        go - makers (k)
        go - materials (m)
        go - segments (g)
        go - stylesheets (y)

        metadata - add (mda)
        metadata - get (mdg)
        metadata - remove (mdrm)

        output.ly - interpret (olyi)
        output.ly - open (olyo)

        output.pdf - open (opdfo)

        package - version (ver)
        package - versions list (verls)

        repository - add (rad)
        repository - clean (rcn)
        repository - commit (rci)
        repository - revert (rrv)
        repository - status (rst)
        repository - update (rup)

    >

The thing to notice is that the amount of whitespace between the two columns is
good now.