Impacted versions:10

Steps to reproduce:
Following the code in https://www.odoo.com/documentation/10.0/api_integration.html both in a fresh install and against 'https://demo.odoo.com/start' trows a type error

Current behavior:
Now I get an error when executing:

```
ids = models.execute_kw(db, uid, password,  'res.partner', 'search',
    [[['is_company', '=', True], ['customer', '=', True]]],
    {'limit': 1})
[record] = models.execute_kw(db, uid, password,
    'res.partner', 'read', [ids])
# count the number of fields fetched by default
len(record)
```

In particular it seems to be a type error (cannot marshal class odoo.tools.float_utils.float_precision)

Expected behavior:
I would expect it to behave as in the documentation

openerp/fields.py
""" set the value of field ``self`` on ``record`` """
        env = record.env
        
        record.ensure_one()
        
        value = self.convert_to_cache(value, record)
        if env.in_draft or not record.id:
            
            spec = self.modified_draft(record)
            
            record._cache[self] = value
            if env.in_onchange:
                for invf in record._field_inverses[self]: