data: Add a top level wrapper for `Linker`. The `family` object is special in that it's "attached" to the current page, so make an object dedicated to that. It removes special code in `Linker`, and makes it possible to go `family.children` directly to get a page's children (i.e. pages in a directory of the same name).

from textile import textile
from piecrust.formatting.base import Formatter


class TextileFormatter(Formatter):
    FORMAT_NAMES = ['textile', 'text']
    OUTPUT_FORMAT = 'html'

    def render(self, format_name, text):
        assert format_name in self.FORMAT_NAMES
        return textile(text)