Removed PackageWrangler.

Use Wrangler instead.

MILESTONE: wrangler inheritance hierarhcy now looks like this:

    Wrangler
        BuildFileWrangler
        DistributionFileWrangler
        MakerModuleWrangler
        MaterialPackageWrangler
        ScorePackageWrangler
        SegmentPackageWrangler
        StylesheetWrangler

Note that this maps exactly to the ...

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

... main score manager libraries.