Avoid misleading the reader by making them believe that it is possible to
process a credit card payment on an invoice. The article talks about the
accounting mechanism (ie. payment registration) and not about the payment
processing.
Closes#173
* by-application (odoo-wise) grouping
* use part of the accounting TOC defined on pad
* support for "internal" tocs & fixup front toc
* various changes and improvements to extensions
May be missing: inherited document banners?