Mark Cost-plus Transactions as 'Invoiced'

This applies to Cost Plus and Cost Plus GMP contracts, which we use exclusively.

We are often need to bill out a contract before all the costs (bills/expenses/timecards/etc) are in. Reasons vary - client's FY closing and they request advance billing, when we pre-bill certain slow to pay customers, or if we reach a milestone under-budget and want to bill out a phase in a GMP project to 100%.

Once the remaining costs come in, they show up on our pre-billing reports and are available for import into future invoices.

Our current workaround is to create dummy invoices, gather up the relevant transactions, then manually adjust the invoice to $0. This is not practical in most cases, and has caused confusion.

I would like the ability to see the billed/unbilled status for timecards and similar transactions be able to manually update the property for ones which are not tagged to an invoice.