Merge branch 'cp/merge-continue'

"git merge --continue" has been added as a synonym to "git commit"
to conclude a merge that has stopped due to conflicts.

* cp/merge-continue:
merge: mark usage error strings for translation
merge: ensure '--abort' option takes no arguments
completion: add --continue option for merge
merge: add '--continue' option as a synonym for 'git commit'

diff --cc builtin/merge.c
Simple merge

diff --cc contrib/completion/git-completion.bash
Simple merge