Allow author of the macro to delegate its view right on the PDF document

This feature is like ...AsAuthor() access. It allows the following improvement:

{{pdfviewer document="private.docname" file="paper.pdf" asauthor="true" /}}

Any user with access to the document containing the above macro will be able to view the pointed PDF file even if it does not have view right on the document containing it, but only if the author of the document containing the macro as view right on it.

When this happen, the buttons on the PDF viewer allowing download and print are removed.