commands: introduce a new command to edit commit metadata
This patch introduces metaedit, a command to metadata of a set of revisions
without updating the working copy. This is particularly relevant for
repositories where changing the parent of the working copy is time-consuming.
We could add more stack manipulation operations to metaedit in the future.
syntax: re
/figures/[^/]+\.png$
^html/
\.pyc$
~$
\.swp$
\.orig$
\.rej$
\.err$
^tests/easy_run.sh$
^build/
^MANIFEST$
^docs/tutorials/.*\.rst$
\.ico$