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
return bool(self.store or self.search or (self.column and self.column._fnct_search))
    @property
    def _description_sortable(self):
        return self.store or (self.inherited and self.related_field._description_sortable)
    def _description_string(self, env):
        if self.string and env.lang:
            model_name = self.base_field.model_name
            field_string = env['ir.translation'].get_field_string(model_name)
            return field_string.get(self.name) or self.string
        return self.string
    def _description_help(self, env):
        if self.help and env.lang:
            model_name = self.base_field.model_name
            field_help = env['ir.translation'].get_field_help(model_name)
            return field_help.get(self.name) or self.help
        return self.help
    
    #
    
    #
    def to_column(self):