Refactor code.

[morngrar]

I can see no reason for outputting intermediate files with this script. Code should be refactored into outputting straight to out.pdf.

[morngrar]

Possibly found a way to do this without monkey-patching PyPDF2: Using io.BytesIO instead of intermediary files. PyPDF2 should see these objects as regular files. Haven't tested this yet, though.