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

""" Many2many field; the value of such a field is the recordset.
        :param comodel_name: name of the target model (string)
        The attribute ``comodel_name`` is mandatory except in the case of related
        fields or field extensions.
        :param relation: optional name of the table that stores the relation in
            the database (string)
        :param column1: optional name of the column referring to "these" records
            in the table ``relation`` (string)
        :param column2: optional name of the column referring to "those" records
            in the table ``relation`` (string)
        The attributes ``relation``, ``column1`` and ``column2`` are optional. If not
        given, names are automatically generated from model names, provided
        ``model_name`` and ``comodel_name`` are different!
        :param domain: an optional domain to set on candidate values on the
            client side (domain or string)
        :param context: an optional context to use on the client side when
            handling that field (dictionary)
        :param limit: optional limit to use upon read (integer)
    """
    type = 'many2many'
    _slots = {
        'relation': None,               
        'column1': None,                
        'column2': None,                
        'auto_join': False,             
        'limit': None,                  
    }
    def __init__(self, comodel_name=Default, relation=Default, column1=Default,