When you select an invoice method different than 'No Invoice', all the
parts lines except the 'Remove' ones and the fee lines will be invoiced.
When you print a quotation, the price of parts and fees is shown
only if you have an invoice method (you only have the quantity if you
don't invoice)
The invoice is available through a stat button.
The price of removed parts is set to 0.0 by default as it won't be
invoiced.