Add some Vim auto-completion tests, and fix a couple of bugs - one especially...
Add some Vim auto-completion tests, and fix a couple of bugs - one especially annoying one is when completion is invoked automatically and we attempt to repeat it via '.' - only the leading portion that we had typed of the completion would be repeated, not the whole thing. Also, begin work on making the completion list wrap-around: this currently fails as https://git.reviewboard.kde.org/r/109647/ has not yet been committed. CCBUG:311831