In accounting, replaces billingParty by billToParty which is more clear (actually billingParty was a wrong name)
Introduces a billToPartyTaxId, this is now mandatory in at least France for VAT (http://vosdroits.service-public.fr/professionnels-entreprises/F31808.xhtml), and might exist in other countries as well

git-svn-id: https://svn.apache.org/repos/asf/ofbiz/trunk@1614562 13f79535-47bb-0310-9956-ffa450edef68