PDF annotation fixes

[ublefo]

Upstream issue

doubtfire-lms#326

Limitations

This fix will only preserve links (hyperlinks and internal links) and nothing else. This is a limitation of the TeX packages we have available, both pax and newpax can only extract links and nothing else. The TeX engine can insert annotations with a package like pdfcomment, but we cannot extract them from the PDFs we are including.

Currently there are no better solutions unless we stop processing PDF submissions with the TeX engine.

Main tasks

• Update erb templates
  • Global preamble app/views/layouts/application.pdf.erbtex
  • Task submission PDF template app/views/task/task_pdf.pdf.erb
  • Portfolio PDF template app/views/portfolio/portfolio_pdf.pdf.erb
• Update installation script to install newpax with tlmgr
• Update installation script to patch the current version of newpax (call tlmgr info --only-installed --data cat-version newpax and ensure we are only patching v0.52)
• Ensure our GhostScript compression calls will preserve these links (ImageMagick can't preserve them)

Nice to have

• PDF test submission files with annotations (links) and unit tests that verifies generated PDFs still has annotations

[ublefo]

doubtfire-lms#389 (merged)