This makes report registration more uniform, and report rendering be possible
through the ORM (and thus the model service, instead of the report service).
To register a report, always use the database, i.e. a <report> tag within an
XML file. The custom parser, if any, will be specified in the database.
Previously specify a custom parser, the report was declared in Python.
Each model exposes a print_report() method, which will take the report name (as
many report can be defined on a single model) in argument.
bzr revid: vmt@openerp.com-20130327161129-6e7jz7l3lx7z1t18
23d672dfc3