Set Customer's Request Number [Custom Field] as Filename for PDF file.

Most customers request lots of offers from different companies. Usually we therefore name quote files so that the filename contains the quote request id a company files the procurement process under. This increases our conversion rate as it allows customers to more easily find our offer file on their PC. It also makes customers happier, as its easy for them to rquest products. As of now we change file names manually which is a hassle. Ideally we are able to assign our custom fields to be file names or extensions thereof.