evolve: store obsmarkers to be deleted in evolvestate There are operations which don't create a new node rather they just obsolete one of the unstable node in favour of existing one. In such cases if a further resolution leads to conflicts and user calls `evolve --abort` or `evolve --stop`, we might need to delete that obsmarker. So let's store such obsmarkers in the evolvestate.

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/