This commit adds a page view for invoices on the customer portal. Layout
is based on the invoice report to closely match what is already done in
Odoo. It replaces the old controller that returned only the pdf.
Customers should now be able to receive both.
Future commits will improve invoice page view notably in account_payment
while adding payment options in account customer portal.
* rename some files according to guidelines;
* clean template name to clean their ordering and ease template browsing;
* use html type for mail templates body instead of cdata;
* clean html for mail templates introduced at 96da10de6cc20486b3e37fd4c6c88eb61cbb919c;
No horse has been harmed and no functional change performed.
Christophe Simonis