obslog: add the operation to the Obslog output The operation is helpful when debugging a case where we don't know how we ended up in this case while effect-flag are useful to understand what semantic changes happens to a changeset. Add the operation when displaying an obs-marker in the following form: `rewritten as X using amend` The other proposal is interesting but seems harder to internationalize and might requires update each time we introduce new operation: `Amended as X` Let's use the first proposal right now.

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

^docs/training/graphs/
^docs/training/html/
^docs/training/index.html
^docs/training/graphviz-images/
^docs/training/img/
^docs/training/output/
^docs/training/pandocfilters/