Return an OrderedDict (to preserve script run order) which maps
    filenames coming from a single local source directory to a single
    target directory.  Most useful for scripts, whose location when
    run is often unimportant, and so can all be placed in common
    directory.

def makemap(filenames, sourcedir, targetdir=None):

    """Return an OrderedDict (to preserve script run order) which maps
    filenames coming from a single local source directory to a single
    target directory.  Most useful for scripts, whose location when
    run is often unimportant, and so can all be placed in common
    directory."""

    if targetdir is None: targetdir = DEFAULT_TARGETDIR
    return OrderedDict(
        (join(targetdir, f),  join(sourcedir, f)) for f in filenames)