[FIX] models: rename method `perm_read` to `get_metadata`.
[IMP] base: update "base.module.update" to new api.

Also rename fields to avoid warnings
[FIX] test_new_api: fields with delegate=True must be required.
[FIX] product: rename function field function to avoid conflict with column name
[FIX] calendar: rename function "calendar_last_notif_ack" on "res.partner" to avoid conflict with column name
[FIX] mail: rename "read" field on "mail.notification"
[FIX] account_payment: rename function of function fields "info_{owner,partner}"