grab: add a command to grab a commit and update to it
This patch adds anew command `hg grab` which will pick a commit and put it on
the top of the working directory parent and updates to it.
Earlier grab was an alias for `hg rebase -r <rev> -d .` which is now deleted to
make sure `hg grab` resolves to the grab command and that alias.
Continuing interrupted grab functionality is also there using the evolvestate
class.
Tests are also added for the new introduced command.
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/