26 Complete full lines

Expands on #38.

Towards #26.
Actually my original concern is not valid. But the problem you bring up is definitely tricky. I'd say that for full lines, the user really does want the *entire* line, including non-word chars. This would be a problem for any completion engine that does not do partial matches (I'm guessing the built-in omni complete), but it shouldn't be a problem for Neocomplete and definitely not for Unite.