added function to get unformatted/unchunked text

- moved formatted function to poppler_pdf_formatted_text
- new one is poppler_pdf_text
- docs and tests not fixed yet
CI updated, only using 5.5 now

+ added valgrind memory option to TESTS
gitignored everything that survives make distclean
made file opening test more portable
new sample PDF + source ODT + fixed tests