debugobsconvert: also deduplicate markers in the process Various bug allowed identical or semantically identical marker to be added to the repository. So we also filter duplicates when converting.

syntax: re
/figures/[^/]+\.png$
^docs/build/
^docs/html/
^html/
\.pyc$
~$
\.swp$
\.orig$
\.rej$
\.err$
^tests/easy_run.sh$
^build/
^MANIFEST$
^docs/tutorials/.*\.rst$
\.ico$