Refactor form_to_db_schema_options()

[seanh]

Having two methods form_to_db_schema(self) and form_to_db_schema_options(self, options) seems unnecessary, why not just have form_to_db_schema(self, options=None)?

Fixing this might break existing extensions although I don't think any are using form_to_db_schema_options() so it should be okay.

The same thing goes for db_to_form_schema_options().

Also why are we passing a dict 'options' that always contains the same three keys 'api', 'context' and 'type'? Why not three params api=None, contenxt=None, type=None?