Merge branch 'jc/am-options'

* jc/am-options:
  git-am: rename apply_opt_extra file to apply-opt
  Test that git-am does not lose -C/-p/--whitespace options
  git-am: propagate --3way options as well
  git-am: propagate -C<n>, -p<n> options as well
  git-am --whitespace: do not lose the command line option