Key bindings for interactive rebase

Hi Tim,

here are some key bindings that I use to quickly change the actions for individual commits in interactive rebase. I simply used the shortcuts for the commands explained in the comment block like this:
`<c-p><c-p>` for pick
`<c-r><c-r>` for reword
`<c-e><c-e>` for edit
`<c-s><c-s>` for squash
`<c-f><c-f>` for fixup
`<c-x><c-x>` for exec
`<c-k><c-k>` for commenting out a line (delete the commit)

Feel free to adapt the key mappings to your liking.

Best regards,
 Gabriel