Produce full PDFs of notes and annotated PDFs (including new v6 format)

[hersle]

With these changes, rmtool.py convert-all -r my_raw_remarkable_files/ -o outdir/ -d successfully converts every (pre-v6 and v6) document on my RM to PDF. It produces sane document sizes, works for pure RM notebooks, annotated PDFs and mixes thereof, handles foreground notes that extend outside the background PDF's area, etc. It is an attempt to make the renderer "universal" again, as it was before the new v6 format, and like the RM USB web interface renderer.

It requires rsvg-convert instead of inkscape (in the future I think it would be a good idea to avoid all these CLI tools), PyPDF2 instead of pdfunite and rmscene with this small modification.

I am interested in whether it works for someone else's RM.

[haglobah]

Looking good! However, sometimes the conent['redirectionPageMap'] is just empty, which causes the script to crash with an IndexError.
Any idea why the .content file sometimes has this redirectionPageMap filled, and sometimes it doesn't?