adds support for diff-preparing all the books
adds support for diff-preparing all the books

instead of running it for one book at a time

Connexions/cnx-recipes,Connexions/cnx-rulesets,Connexions/cnx-recipes,Connexions/cnx-rulesets,Connexions/cnx-recipes,Connexions/cnx-rulesets,Connexions/cnx-recipes,Connexions/cnx-recipes,Connexions/cte,Connexions/cte,Connexions/cnx-rulesets