Add tests from Caradoc

[XVilka]

Caradoc is a parser and validator of PDF files written in OCaml. Caradoc provides many commands to analyze PDFs, as well as an interactive user interface in console. They have an interesting set of the PDF files, which can make a good testcases for you

The test files are here: https://github.com/caradoc-org/caradoc/tree/master/test_files

See more information in their presentation:

• http://spw16.langsec.org/slides/guillaume-endignoux-slides.pdf
• http://spw16.langsec.org/papers/endignoux-caradoc.pdf