Rather than assume the user named their neovim/neovim remote "upstream",
parse the information from "git remote -v".

The new version of the lua client uses libmpack as a backend, and some test
scripts had to be updated to reflect that.

Make get_vim_sources fetch the whole repository (it's not THAT big) so we can
pick up all the patches. The regexp didn't pick up the NA patches if there was a
comma after NA, so I extended it (I allowed arbitray things after NA, so maybe
someone can write a comment or so, should not lead to confusion).

This was not the correct way to fix the issue.

* Calling "vim-patch.sh -p" on a checked-out branch already created with
  "-p" will re-use the branch and append commits.

* Fetch upstream/master before checking out branch on first call of "-p".

* Reverted creation of commit in submit step ("-s") to previous behavior:
  Create an empty commit with correct commit message when "-p" is called.

* Submitting a pull request with "-s" will create a correct pull request
  message even if multiple patches have been ported in one single branch
  with "-p".

When calling "vim-patch.sh -s" on a checked-out branch created with
"vim-patch.sh -p", create commit from staged changes, push to origin,
create pull request (using hub), and clean up patch files.