git hooks for IPython
add these to your .git/hooks
For now, we just have post-checkout and post-merge,
both of which just update submodules,
so make sure that you have a fully synced repo whenever you checkout or pull.
To use these hooks, you can symlink or copy them to your .git/hooks directory.
ln -s ../../git-hooks/post-checkout .git/hooks/post-checkout
ln -s ../../git-hooks/post-merge .git/hooks/post-merge