title: PDFsharp save to MemoryStream
body: <p>I want to save a PdfSharp.Pdf.PdfDocument by its Save method to a Stream, but it doesn't attach the PDF header settings to it. So when I read back the Stream and return it to the user, he see that the PDF file is invalid. Is there a solution to attach the PDF header settings when PDFsharp saves to memory?</p>