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
_column__module = property(attrgetter('_module'))
    _column_copy = property(attrgetter('copy'))
    _column_select = property(attrgetter('index'))
    _column_manual = property(attrgetter('manual'))
    _column_string = property(attrgetter('string'))
    _column_help = property(attrgetter('help'))
    _column_readonly = property(attrgetter('readonly'))
    _column_required = property(attrgetter('required'))
    _column_states = property(attrgetter('states'))
    _column_groups = property(attrgetter('groups'))
    _column_change_default = property(attrgetter('change_default'))
    _column_deprecated = property(attrgetter('deprecated'))
    _column_group_operator = property(attrgetter('group_operator'))
    
    #
    
    #
    def null(self, record):
        """ Return the null value for this field in the record format. """
        return False
    def convert_to_cache(self, value, record, validate=True):
        """ Convert ``value`` to the cache format; ``value`` may come from an
        assignment, or have the format of methods :meth:`BaseModel.read` or
        :meth:`BaseModel.write`. If the value represents a recordset, it should
        be added for prefetching on ``record``.
        :param bool validate: when True, field-specific validation of ``value``
            will be performed
        """
        return value
    def convert_to_record(self, value, record):