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).

#!/bin/sh

CUR_DIR="$( cd "$( dirname "$0" )" && pwd )"
CHEF=${CUR_DIR}/../bin/chef
OUT_DIR=${CUR_DIR}/../piecrust/resources/messages
ROOT_DIR=${CUR_DIR}/messages

$CHEF --root=$ROOT_DIR bake -o $OUT_DIR
rm ${OUT_DIR}/index.html