[FIX] sale_stock: make related field `product_tmpl_id` on `sale.order.line` readonly
[FIX] sale_stock: make related field `product_tmpl_id` on `sale.order.line` readonly

This prevents an access right error when saving a sales order after changing
its delivery method.  The latter updates sale order lines by an onchange, which
causes the unexpected update on the field.

bplancher/odoo,storm-computers/odoo,microcom/odoo,optima-ict/odoo,bplancher/odoo,dfang/odoo,Elico-Corp/odoo_OCB,Elico-Corp/odoo_OCB,microcom/odoo,storm-computers/odoo,stephen144/odoo,ygol/odoo,microcom/odoo,sysadminmatmoz/OCB,hip-odoo/odoo,ygol/odoo,sysadminmatmoz/OCB,optima-ict/odoo,dfang/odoo,laslabs/odoo,sysadminmatmoz/OCB,sysadminmatmoz/OCB,bplancher/odoo,stephen144/odoo,laslabs/odoo,hip-odoo/odoo,stephen144/odoo,Elico-Corp/odoo_OCB,storm-computers/odoo,ygol/odoo,sysadminmatmoz/OCB,laslabs/odoo,microcom/odoo,hip-odoo/odoo,sysadminmatmoz/OCB,bplancher/odoo,dfang/odoo,optima-ict/odoo,hip-odoo/odoo,storm-computers/odoo,Elico-Corp/odoo_OCB,hip-odoo/odoo,dfang/odoo,stephen144/odoo,optima-ict/odoo,laslabs/odoo,optima-ict/odoo,stephen144/odoo,sysadminmatmoz/OCB,microcom/odoo,storm-computers/odoo,dfang/odoo,ygol/odoo,laslabs/odoo,ygol/odoo,ygol/odoo,laslabs/odoo,ygol/odoo,dfang/odoo,bplancher/odoo,bplancher/odoo,microcom/odoo,Elico-Corp/odoo_OCB,hip-odoo/odoo,optima-ict/odoo,Elico-Corp/odoo_OCB,storm-computers/odoo,stephen144/odoo