[Add,imp]:Remove expense 'sheet' concept

Task: https://www.odoo.com/web#id=9989&view_type=form&model=project.task&menu_id=3942&action=327
Pad: https://pad.odoo.com/p/r.bd4JuNZUZclDd9oL
this form also work for Create Expenses, I think you need to apply state based attrs because some fields are readonly and some fields are invisible in Submitted expense form(No need of two forms for same model which are almost same)