updated git cloning URL
update to repository names
changed name to many2many relation table to avoid conflict with salon_spa module.
PEP8 compliance.
removed translation for removed field (appointment_id).
changed pos.order.line/planning.appointment relation and unlinking validations to order_line_id. removed use of appointment_id.
PEP8 compliance.
changed cashbox opening method and minor udpate to comment.
PEP8 compliance.
replaced use of appointment_id with order_line_id. added new closed_date field and [] to ids comparison to avoid warnings. changed name for relation table to avoid conflict with salon_spa module.