stablerange: move revs computation within the main class
We still need to compute the revision withing a range when we slice a merge.
This is the last large logic that remains in the individual class and we migrate
is on the main class.
syntax: re
/figures/[^/]+\.png$
^html/
\.pyc$
~$
\.swp$
\.orig$
\.rej$
\.err$
^tests/easy_run.sh$
^build/
^dist/
^MANIFEST$
^docs/tutorials/.*\.rst$
\.ico$
tests/\.testtimes