Describes possible implementation of invoicing
New table
invoice:
| field | comment |
|---|
| project | |
| name | |
| status | new, open, paid, booked, dropped, etc. |
| short | e.g. invoice number |
| description | |
| date_sent | |
| date_due | |
| date_pay | |
| amount_clear | |
| tax_rate | |
| booked_as | short name for id, quartal etc. |